Everseal Stationery Products Ltd v Document Management Solutions Ltd & Ors

The Claimant (“Everseal”) is the proprietor of UK Patent No. 2,340,073 (“the Patent”) which claims a type of business form referred to at the trial as a ‘mailer’. A mailer is a form, letter or other type of business communication which is folded after completion, sealed by means of adhesive around its periphery and then sent through the post.

Everseal alleges that the First Defendant (“DMSL”) has infringed the Patent by making and disposing of mailers falling within the claims of the Patent. The Second to Fifth Defendants are officers of DMSL alleged to be jointly liable for DMSL’s infringements. By agreement between the parties I stayed the proceedings against the Second to Fifth Defendants in an Order dated 29 May 2014, to be heard at the inquiry or account if there is one.

The Patent has some history. On 22 February 2010 Mastermailer Stationery Limited (“Mastermailer”), a stationery company as its name implies, brought an action in the Patents County Court to revoke the Patent. The defendant was Jonathan Horler, identified as inventor in the Patent. It emerged after the action started that the first proprietor was Mr Horler’s company, though it had assigned the Patent to Everseal. Everseal was joined as second defendant. Everseal counterclaimed for infringement of the Patent by Mastermailer in relation to sales of a mailer I will call ‘Mailer 1’. On 24 March 2010 Everseal applied to amend the Patent.

There arose an issue as to which of Mr Horler and Everseal was the rightful owner of the Patent. His Honour Judge Birss QC directed that this should be resolved as a preliminary point and in a judgment dated 21 December 2011 he ruled that Everseal was the rightful owner. Following this judgment Mastermailer and Everseal settled their differences by means of a Tomlin Order dated 21 November 2011.

Within two and a half weeks hostilities resumed. On 8 December 2011 Mastermailer brought a fresh action against Everseal with Robert Gooch, a director of Everseal as second defendant. Mastermailer alleged unlawful threats of proceedings for patent infringement and also sought a declaration that Mailer 1 did not infringe the Patent. Subsequently Mastermailer added a claim for revocation of the Patent. On 25 October 2012 Everseal made a new application to the court to amend the Patent, in a form slightly different from that earlier proposed. The amendment was not opposed by Mastermailer or the Comptroller subject to a minor point which was resolved.

In relation to all of this Judge Birss ruled that there should be a trial of a second preliminary point, namely whether sales of Mailer 1 infringed the Patent. At the trial of that preliminary point Judge Birss had also before him the question whether the Patent should be amended. Amendment was unopposed so argument only concerned the Patent as proposed to be amended, specifically claim 1.

In a judgment dated 16 January 2013 (“the Mastermailer Judgment”) Judge Birss held that Mastermailer’s claim to a declaration failed – he was not satisfied that Mailer 1 fell outside the scope of claim 1 in its proposed amended form. The proposed amendments to the Patent were allowed.

Mastermailer had been supplied with Mailer 1 by DMSL. Supplies stopped in June 2013. No doubt with the Mastermailer Judgment in mind, DMSL developed another mailer, which I will call ‘Mailer 2’. This was manufactured and sold directly to stationers by DMSL from June 2013. A third version, ‘Mailer 3’, was made and sold by DMSL from some time in 2014.

The present proceedings were brought by Everseal on 27 November 2013. Everseal alleges that Mailers 1, 2 and 3 all infringe the Patent. The Defendant counterclaims for revocation of the Patent and raises other arguments on Everseal’s right to claim relief. Everseal has asserted the independent validity of claims 1 and 7 of the Patent. By the time of the trial the issues came down to these:

Ms Kathryn Pickard appeared for Everseal and Mr Jonathan Hill for DMSL.

Even though Judge Birss allowed amendment of the Patent in the Mastermailer judgment, the Patent has still not been amended. The Order following that judgment was not in the bundles for the trial before me but I was told by counsel that it contained no order that the Patent should be amended. The best guess by counsel on both sides was that the order for amendment had been omitted by oversight when the draft was settled after trial (neither Ms Pickard nor Mr Hill was instructed in that trial). I was told that Mr Foghlu, the director of Everseal, later applied to the Intellectual Property Office to have the Patent amended in the form allowed by Judge Birss but was informed by the IPO that this could not be done without an order of the court. He thought that this would be best left for this trial. The point of mentioning it now is that although for simplicity I will sometimes refer to the ‘unamended’ and the ‘amended’ Patent, strictly this will mean respectively the Patent in its current form and the Patent as proposed to be amended.

The Patent is concerned with what is claimed to be a novel means of sealing mailers employing a type of adhesive not previously used for that purpose. The specification refers to various means of sealing which formed part of the prior art. The first is a water-activated adhesive. Mailers using such adhesives were referred to at the trial as ‘lick-and-stick mailers’. The sender licks the adhesive region, folds the mailer so that the wet adhesive contacts the opposite region of the mailer and binds the mailer in the closed form, suitable for posting, as the adhesive dries.

The second is a silicone-based ‘contact adhesive’. A contact adhesive is one which sticks to itself but not to other materials. In the case of silicone-based contact adhesives bonding requires a sealing machine which applies a high pressure to the opposing layers of adhesive to ensure that they stick. Use of mailers having this type of adhesive is therefore only possible if a high pressure sealer is used, with the expense that entails. These were called ‘pressure seal mailers’.

A known third type of adhesive is ‘tacky’ in nature. This means that it is sticky to the touch and will bind to materials other than itself. Mailers using this type of adhesive incorporate a strip of material covering the adhesive layer which is peeled off by the user just before the mailer is folded, so that the adhesive sticks to the opposite region of the mailer. These were referred to as ‘peel-and-stick mailers’.

Although not mentioned in the Patent, it was common ground that the prior art included a fourth type of mailer. These used a type of adhesive which had to be exposed to a high temperature to be activated. It was therefore necessary to use a high temperature sealer to seal the mailer in its closed folded form for posting.

Having set out the prior art (or most of it) the Patent as amended goes on to say this (at page 2, line 7 to page 3, line 5):

“What we now propose is a new and useful business form or mailer of the type described above which uses, as the or each adhesive region, a non-tacky layer of a dry self-sealing contact adhesive which self-seals irreversibly to an opposed adhesive layer of the same kind, when the form has been folded to its folded condition, under a sealing pressure applied on that region which is a finger pressure, or alternatively stated, a pressure of 500 kPa or less or 300 kPa or less, but preferably at least 10 kPa.

A form or mailer as proposed is in practice a dry seal form or mailer that can be sealed by hand without requiring the use of a sealing machine. Sealing machines are expensive, typically being engineered to exert pressures in the range 20 to 60 MPa (3000 to 8000 lb/in²) as required by the conventional dry-seal contact adhesives. Thus, the present proposals open the way for example to small-scale use of direct mail by organisations who for one reason or another cannot run a sealing machine. The proposal also opens the way to fold, seal and return response forms which can easily be used by the ordinary recipient without the need to wet an adhesive strip – a common source of discontent.”

The essence of the claimed invention is a mailer with an adhesive which is a ‘non-tacky’ contact adhesive but which, unlike silicone-based contact adhesives, will bind to itself (‘self-seal’) under merely finger pressure. Importantly the specification says that the adhesive ‘self-seals irreversibly’ under such pressure. Finger pressure means specifically 500 kilopascals or less, though preferably at least 10 kPa.

It is sufficient to set out claims 1 and 7 in their amended forms. I also include claim 6 to give sense to claim 7:

“1.

A business form with an adhesive closure having one or more adhesive regions for holding the form on a folded condition, characterised by the use on the adhesive region of a non-tacky layer of a dry self-sealing contact adhesive, which in the folded condition self-seals irreversibly to an opposed adhesive region also carrying a said contact adhesive, the adhesive being selected to self-seal irreversibly under a pressure of 500 kPa or less.

6.

A business form according to any one of the preceding claims made from a paper sheet which is laser-printable in which said contact adhesive is an elastomer latex adhesive.

7.

A business form according to claim 6 in which the adhesive is a natural rubber latex adhesive stabilised with ammonia.”

In the Mastermailer Judgment Judge Birss identified the skilled person as a team concerned with producing business forms, including someone who is an adhesive specialist. Ms Pickard submitted that the same team was appropriate to this case and Mr Hill did not dissent. Judge Birss did not specify the characteristics of the other member or members of the team but it seems to me this will be one person skilled in the business of the manufacture of stationery, including mailers.

Peter Caton was DMSL’s expert witness. He said that usually a stationery business would not have in-house expertise in adhesives and would consult a specialist in that field when advice was needed as to how a particular objective might be achieved. I accept that this is the way the notional team of skilled persons would work in the real stationery world.

Both Mr Caton and James Palmer, Everseal’s expert, worked in the field of adhesives and so could give evidence about that part of the skilled team. They had a phone discussion on 20 January 2015, having read each other’s first expert report, and substantially agreed the common general knowledge of the skilled adhesives person. This appears from written notes of their discussion and their reply expert reports.

At the trial leading to the Mastermailer Judgment, Mastermailer had called Robert Morris as an expert. He is the operations manager at DMSL and now the Fifth Defendant in these proceedings. Mr Morris’s expertise is in the same field as that of the other member of the notional skilled team, i.e. the manufacturer of stationery. Mr Palmer acted as expert witness for Everseal before Judge Birss. In other words the experts on opposing sides in that trial came from different fields: one from stationery, the other from adhesives. Mr Morris gave evidence in the present action, but solely as a witness of fact.

Judge Birss set out paragraphs from Mr Morris’s report regarding in the common general knowledge of the person skilled in the art of stationery manufacture at the relevant date, 31 July 1998. This evidence was accepted and so I set it out here.

“13.

To the best of my knowledge, mailers first emerged in the 1970s/1980s with the spread of the computer and computer printer in offices. Early printers were sprocket fed with continuous lengths of fan-folded, perforated paper. Business forms manufacturers and other engineering type companies (i.e PFE/Neopost referred to above) developed machines that could take the output of these printers and then ‘burst’ (separate) the forms to individual sheets. Many of these forms would ultimately be inserted individually into conventional envelopes for posting. Similarly, with the development of pressure seal and pressure sensitive adhesives, forms could be mailed without the use of an envelope. Some manufacturers sold these machines together with fan-folded business forms.

14.

Early mailer technology changed with the spread of laser printers able to print on an individual A4 sheets. Business forms manufacturers responded with single sheet ‘pressure seal’ mailers made from laser printer paper. Pressure seal adhesive is dry and non-tacky to the touch but will seal strongly to itself (a ‘contact’ adhesive) if two opposing layers are placed under high pressure. The seal produced by a pressure seal adhesive at pressure is so strong that it is practically impossible to re-separate bonded layers of paper without damage to the paper. In the industry this is known as ‘fibre tear’. This has always been a standard measure of good bond strength in sealable mailers.

15.

The advantage of pressure seal mailers was that they could be run through laser printers like any other sheet of paper. The disadvantage was that they needed an expensive machine to generate the high pressures needed to seal them.

16.

From memory, Paragon Business Forms Limited was the first company to start selling pressure-seal mailers in the UK in the late 1980s/early 1990s. When I moved to Laser Image Limited in 1988 or 1989, Bowater was in the process of developing its own pressure-seal mailing system. One of our main tasks at Laser Image was to run trials of various paper and adhesive types, alone and in combination, as part of this development.

17.

Following the rise of the pressure-seal mailer, in the 1990s ‘pressure sensitive’ mailers began to become popular as well. A pressure sensitive mailer incorporates a pressure sensitive adhesive strip covered by a protector (usually made of silicone paper). Pressure sensitive adhesive is what is known as ‘live’ adhesive. It is tacky to the touch, does not generally set and will remain usable for a long period of time (assuming it is not contaminated). This type of mailer was capable of being passed through a printer in order to be filled in. In order to seal it, the protector is peeled off, the form is folded and then the adhesive can be pressed by hand directly against an opposing paper surface to seal the mailer. The same system is used in envelopes today. The seal produced by a ‘live’ pressure sensitive adhesive at low pressure is also strong enough to make it very difficult to re-separate the bonded layers without causing fibre tear.

18.

The advantage of pressure sensitive mailers is that they could be sealed manually. The disadvantage was the need to remove the protective paper strip, which becomes time consuming if one has a batch of mailers to seal.

19.

In 1998 I would estimate that pressure seal mailers [had] about 70% of the mailer market, pressure sensitive mailers about 20% (although this share was growing). The remainder was made up mostly of ‘re-moist’ mailers and heat sealable mailers. Re-moist mailers incorporated wettable adhesive which would dry to an opposing paper layer to form a bond, i.e. basic envelope and postage stamp technology. The adhesive on heat sealable mailers looked very similar to re-moist mailers, but the adhesive was activated by the application of heat through a special machine. ”

Judge Birss then went on to make further findings about the common general knowledge and to quote another aspect of Mr Morris’s evidence which he accepted:

“[11] One thing not mentioned expressly by Mr Morris, but which is self-evident, is that the point of this inability that he has referred to, to re-separate the bonded layers of paper in a mailer, is because one of the key uses of these mailers is for sending secure and confidential information, such as using them as pay slips. The point of this is that while one cannot prevent a third party from opening the mailer before it reaches the addressee, on the other hand, if the mailer cannot be resealed without that tampering being evident, then that will discourage the tampering.

[12] Something that was not common general knowledge was a particular expedient used today to make tampering evident. This is the use of so called ‘anti-tamper slits’. Mr. Morris said the following.

“22.

I have been asked specifically whether mailers incorporating ‘anti-tamper slits’ or ‘tamper evident slits’ were common general knowledge in July 1998. ‘Anti-tamper slits’ are slits cut into the adhesive bearing paper of a mailer in order to create a line of weakness. The purpose of such slits is to ensure that if anyone tries to re-open a sealed mailer the paper will tear. This prevents a mailer being re-opened and re-sealed without this being evident.

The notes of the present experts’ phone conversation indicates that Mr Caton and Mr Palmer did not feel themselves qualified to challenge at least aspects of what Mr Morris had said. In the event none of the paragraphs from his report and the further observations of Judge Birss quoted above were challenged and I take them to be a sound guide to the common general knowledge of the stationery member of the skilled team in July 1998.

There was no dispute about the law: I must apply the approach set out by Lord Hoffmann in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2004] UKHL 46; [2005] RPC 9, as further explained by the Court of Appeal in Virgin Atlantic Airways Ltd v Premium Aircraft Interiors UK Ltd [2009] EWCA Civ 1062; [2010] RPC 8.

I have already referred to the agreed meaning of ‘contact adhesive’. Equally it was not in dispute that a ‘dry’ adhesive means the same as a ‘non-tacky’ adhesive (‘tacky’ is discussed above) and that the adhesive is ‘self-sealing’ if two layers of adhesive bind when brought into contact.

It was also not in dispute that the word ‘selected’ in claim 1 implies that the adhesive must characteristically cause the mailer to self-seal irreversibly. That is to say irreversible self-sealing will be the usual result when using the adhesive, while not ruling out the possibility of failures to self-seal irreversibly for exceptional reasons. In that sense the term ‘selected’ requires a consistency in the performance of the adhesive.

The sole argument on construction in this case is about the meaning of ‘irreversibly’ in claim 1. The specification gives guidance at page 3, lines 6-10, a part of the specification to be amended. The proposed amendments were to some extent relevant to the argument and so I show them here:

“The reference above to an irreversible self-seal is to be interpreted as meaning that subsequent re-separation of the layers results in disruption at least of the adhesive structure, if not also in the base material.”

As this shows, in the Patent’s unamended form ‘irreversible’ sealing requires that only the adhesive structure is disrupted upon ‘re-separation’ of the layers, i.e. when the mailer is opened for the first time. The best guide to what is meant by ‘base material’ comes immediately after the passage from page 3 quoted above:

“The basis material of the form is a paper sheet.”

The change from ‘base material’ to ‘basis material’ is not helpful, but this is not a specification drafted throughout with care and precision. No meaning of ‘base material’, other than that one, was suggested to me, so I take it to be the paper from which the mailer is made.

Everseal’s position with regard to the meaning of ‘irreversible’ was that Judge Birss had correctly construed the term in the Mastermailer Judgment and there was little more to be said. This is the relevant passage from that judgment:

“[28] As I have said already, [‘irreversible’] is clearly a reference back to page 3, lines 6–10 of the specification. As amended, the specification makes it clear that one needs both disruption of the adhesive structure and also disruption “in the base material”. If there was just disruption of the adhesive without disrupting the base material, that is not enough.

[29] Even if the disruption to the adhesive meant that it could not really be said that the mailer could be “re-sealed” or stuck back together again, the skilled reader would not think that the patent was referring just to sticking the mailer back together again in that sense. After all, even if you rip the paper you can still stick the mailer back together again. It would just be very obvious what has happened. The disruption referred to does not necessarily prevent re-sticking altogether. The skilled reader would understand that the patent is talking about evidence of tampering. The re-seal is not irreversible if it does not take the mailer back essentially to its pre-opened state; or, in other words, the sort of reversible re-seal that the patent is trying to avoid is reversible in the sense that it makes the mailer look as good as new to a practical extent.

[30] No details of any test are laid down for irreversibility, and in particular for any disruption of the base material, nor are any details set out in the patent as to what test should be carried out to test the numerical limit of the pressures. Nevertheless, the patent is a practical document and aimed at practical people.

[31] The questions which arise in relation to irreversibility are these. First, is disruption in the base material limited to fibre tear? [Counsel for Mastermailer] said it was, because fibre tear was a standard test as part of the common general knowledge. Second, does disruption in the base material include any visually-apparent deformation of the base material? That, essentially, was one or part of [counsel for the defendants’] submissions. Third, does it include any visible disruption like the lifting of ink from one surface to the other? That was a matter that arose in the evidence.

[32] [Counsel for Mastermailer] urged that fibre tear was a well understood and practical test – I accept that – but I am not satisfied that it is fair to read fibre tear into this patent. The skilled reader would have fibre tear as part of his common general knowledge and would assume that the patentee knew of it as well. Thus, the reader is entitled to think that if the inventor had meant “fibre tear”, he could easily have said so. In my judgment, the words “disruption in the base material” do not bear the gloss of “fibre tear”. The words are, as I have said, “disruption in the base material”. That will include deformations, which are substantial enough to make tampering genuinely evident. If the person skilled in the art can see that the whole thing is so wrinkled and deformed that it has obviously been stuck back together again, even if it is not torn, then the original seal was, plainly, irreversible. If fibre tear takes place, then the original seal will certainly have been irreversible, but I do not accept that it is limited to fibre tear. However, I do not think it includes ink transfer. That is going too far.

[33] Furthermore, if [counsel for the defendants’] submission were that any visually apparent deformation of any sort would be enough – I do not agree that the matter can be taken that far either. It is a practical test, and I doubt that the skilled person would, in fact, have any difficulty applying it. For example, one could simply look at the re-sealed mailer and see if it had clearly been opened before. If the disruption of the base material (and the adhesive) makes the tampering evident, then the seal was irreversible.”

Judge Birss’s purposive construction was that an ‘irreversible’ seal was one that could not be opened and then re-sealed without tell-tale signs that this had happened. In relation to the base material, evidence of tampering would include, but should not be limited to ‘fibre tear’; deformation in the base material would do, provided that it indicates that the mailer had been re-sealed.

Both Ms Pickard and Mr Hill were content to agree with Judge Birss that the criterion of noticeable tampering should govern whether there had been disruption. In the amended Patent evidence of re-sealing must be apparent from both the adhesive structure and the base material.

There is something a little unreal, if unavoidable about this. The overall criterion is whether the authorised recipient of the mailer can tell whether the mailer has been previously opened. In reality evidence of earlier opening from either the adhesive structure or the base material would be enough to warn the recipient of what has happened. From that perspective the test in the unamended Patent makes more sense. Nonetheless, the amended specification requires evidence of tampering from both the adhesive structure and the base material, even where earlier opening is totally self-evident from just one of them.

The hypothesis is that a mailer is opened by an unauthorised person, is re-sealed and later it reaches the authorised recipient. Evidence of tampering visible from disruption of the base material will be detected upon receipt. This is easy to understand: does the appearance of the base material give away that the mailer has been opened earlier?

There is a qualification. Mr Hill submitted that the test must contemplate the unauthorised opener of the mailer smoothing the mailer and otherwise doing his best to disguise that he has opened it. Ms Pickard accepted this and it is consistent with Judge Birss’s view, in which he emphasised that this was a practical test for use in the real world. Should the contents of the mailer be read by, say, a nosy neighbour, in reality the neighbour would take a little trouble to avoid being found out. The unauthorised opener is not a master criminal, so the smoothing and other disguising of opening will be strictly limited to what the average person could achieve solely by handling the mailer.

Mr Hill also argued that Judge Birss had too widely construed ‘disruption’ in the context of the base material by holding that it covered ‘deformation’ and the two were not the same. Mr Hill submitted that ‘disruption’ in the context of the base material necessarily implied fibre tear. He took this further by pointing out that the specification refers to ‘disruption of’ the adhesive structure but ‘disruption in’ the base material and, he said, the latter again implied a requirement of fibre tear.

Taking this last point first, I doubt that the skilled person would interpret this specification by finely weighing the semantic implications of which preposition has been used where. Even if he tried to, I don’t think ‘disruption in’ the base material would point the skilled person towards fibre tear significantly more or less than would ‘disruption of’.

As to the more general point, I agree that ‘disruption’ and ‘deformation’ do not mean the same thing but this does not seem to me to be the point. It is common ground that disruption must be assessed by reference to whether tampering can be seen to have occurred. I see no reason to narrow this by adjusting the criterion to whether earlier tampering has been made apparent by a particular means. For the reasons given by Judge Birss, I do not accept that there must be evidence of fibre tear in the base material of an opened mailer in order for the mailer’s seal to be ‘irreversible’ according to this aspect of the test; however, visible fibre tear would be enough to constitute disruption in the base material.

The test as to whether the seal is irreversible is not quite so straightforward in relation to disruption of the adhesive structure. The disruption is that caused by the first opening of the mailer, see page 3 lines 6-10. The first opening might have been by an unauthorised person. If so, the authorised addressee who subsequently re-opens the mailer must be able to tell that earlier opening has occurred. I think this part of the test makes sense if it is intended to exclude from the category of adhesives which self-seal ‘irreversibly’ those which create a seal that can be made and broken at least twice without any visible change to the adhesive structure. Otherwise the authorised addressee who notices disruption to the adhesive structure would not know whether it was caused by earlier tampering or by his own opening of the mailer.

An alternative construction of the adhesive aspect of the test at page 3, lines 6-10 is that disruption of the adhesive structure is to be assessed by inference, as opposed to being directly concerned with what the adhesive structure looks like. It’s about whether the adhesive still works sufficiently well to keep the contents of the mailer secure from inspection. This would be largely a visual test but would involve assessing whether the mailer is securely sealed by the adhesive or whether the binding effect is limited or even wholly absent, such as to suggest earlier opening of the mailer. By inference the adhesive structure would in such a case have been ‘disrupted’.

It’s not necessary for me to pursue this. The parties were agreed that opening of Mailers 2 and 3 resulted in disruption of the adhesive structure, as is apparent from the results of experiments conducted.

In summary, the adhesive self-seals ‘irreversibly’ if, upon receipt of the mailer, the recipient is able to tell from both (a) the adhesive structure (by direct inspection or by inference from inadequate sealing) and (b) the appearance of the base material, that the mailer has previously been opened. If earlier opening would not be betrayed by each of these taken separately, the adhesive did not self-seal ‘irreversibly’ when the mailer was first closed.

It is to be assumed that an unauthorised party who carried out any earlier opening will have taken some limited trouble to disguise what he has done.

I think both the experts were doing their best to help the court. Mr Palmer, as he said himself, had been given only a few days in which to prepare his report. The result was that the report was not always as accurate as it should have been and Mr Palmer was therefore obliged in cross-examination to correct some of what he had said in writing. Because of this Mr Caton was more authoritative than Mr Palmer on adhesives. Neither was in a position to say much about the views of a manufacturer of mailers in July 1998.

Criticisms were made by both Ms Pickard and Mr Hill of the witnesses of fact on the respective opposing sides but in my view all of them were honestly giving evidence as they saw it. The evidence of Jerry Shipley, who used to be Senior Products Manager at the stationery retailer Viking Direct, was particularly relevant to an allegation of prior use. I thought that Mr Shipley gave his evidence in a clear and straightforward manner with no apparent axe to grind on behalf of either party.

DMSL accepts that Mailer 1 falls within claim 1 subject to one argument concerned with whether the adhesive seal is irreversible. Mailer 1 has what were referred to ‘anti-tamper slits’ in the base material. These are slits to which the adhesive is bound that provide zones of weakness such that if an unauthorised attempt to open the mailer is made, the base material will tear. Everseal argues that the seals on Mailer 1 are therefore ‘irreversible’. Up until trial DMSL’s answer was that on a correct construction of the Patent the test of ‘irreversibility’ was concerned solely with the adhesive used and therefore should not take into account any disruption to the base material caused only by the slits. It was an argument run by Mastermailer before Judge Birss and rejected (at [34]-[37]). At trial Mr Hill told me that this point of construction was not longer pursued. It follows that sales of Mailer 1 infringe claim 1 of the Patent.

Infringement of claim 7 would have required Everseal to show that the adhesive used for Mailer 1 was a natural rubber latex adhesive stabilised with ammonia. There was no evidence in this regard one way or the other. I therefore find that that Everseal has not established infringement of claim 7 in relation to Mailer 1.

Evidence in support of the allegation that Mailers 2 and 3 infringed depended on experiments carried out by DMSL. They were originally done towards the end of 2014 though without any record kept of the results by way of photographs or video recording. At a hearing before me on 19 December 2014, at which Everseal was represented by its director Mr Foghlu, he said that he had no objection to DMSL’s experiments, that Everseal had no wish to carry out any of its own and that it would rely on DMSL’s. Very shortly before the trial Everseal, by then advised by counsel and solicitors, had a change of heart. It made an application to conduct its own experiments. I refused the application but directed that the part of DMSL’s experiments which Everseal said was most relevant should be repeated with Everseal present and with photographs taken. I also directed that Everseal were entitled to request amendments or additions to these experiments, such requests not to be unreasonably refused by DMSL.

I record in passing that DMSL and Mr Caton were criticised by Ms Pickard for not keeping proper records of the results the first time round, I think in an attempt to suggest that Mr Caton was not being as straightforward with the court as an expert witness should be. There was nothing in this. I was told that DMSL’s expectation had been that Everseal would ask for DMSL’s experiments to be repeated with both sides present and that photographs or videos would be taken at that stage. No request for repeats was made.

The repeat experiments ordered by me concerned only Mailers 2 and 3. The Mailers were supplied by DMSL and sealed under two different pressures. The first was finger pressure, said to be about 50 kPa. The second method of sealing used mechanical means with a measured pressure of about 480 kPa. The mailers were then peeled apart by hand, one batch after 1 hour and another batch after 23 hours. The results were agreed: in almost every case there was disruption to the adhesive layer and ‘slight curling at the peel corner’. In a few instances further deformation of the base material was observed.

DMSL actively relied on the disruption of the adhesive structure and stated that a particular feature of Mailers 2 and 3 was that in their manufacture a layer of varnish had been applied to the surface of the paper before adding the adhesive. This created a zone of weakness, with the deliberate intention and result of ensuring that only the adhesive structure would be disrupted and not the base material.

Infringement turned on whether ‘slight curling at the peel corner’ qualified as disruption in the base material, i.e. a deformation sufficient to suggest that the mailers had been opened. There was no attempt to re-seal the mailers. Having been sealed and opened, the mailers were either left in their open state or folded back without resealing. It was therefore obvious from the photographs of the repeat experiments that the mailers had been opened.

As I have indicated, I was required to assess whether tampering was evident from disruption in the base material considered in isolation – subject to this: the condition of the base material had to be assessed after there had been some limited attempt to smooth the base material or otherwise to disguise that the mailers have been opened. Yet none of the photographs show mailers after this was done.

In argument I raised the absence of any attempt at smoothing or re-sealing and was directed to a section in the report of the original experiments conducted by DMSL, dated 17 December 2014, which said this:

“Re-sealing

A selective number of tests pieces were attempted to [sic] re-sealed after opening. Those where there was partial adhesive transfer gave a very limited and patchy seal. Those where there was total adhesive transfer gave no seal at all.”

The report of the original experiments suggests that re-sealing is either always or sometimes impossible. It might conceivably be inferred that curling of the type revealed in the repeat experiments is likely to remain sufficiently marked, even after smoothing, so as to indicate opening of the mailers. This would mean there had been disruption in the base material and that the adhesive had sealed irreversibly. But I cannot know whether this was the case. Anyway the relevant experiments at trial were the repeat experiments at which results were recorded.

To some limited extent there was an attempt at smoothing the mailers in the repeat experiments. None of this was photographed either. In passing Mr Caton’s report of the repeat experiments, dated 23 February 2015, says this:

“On a number of mailers where paper curl was noted after opening after one hour, cursory attempts were made both by myself and Mr Poore [DMSL’s solicitor] to see if it may be possible to reverse this.”

The following is recorded under the heading ‘Observations’:

“It was noted that on mailers where curl had occurred this could be reversed so that the mailer lay flat.”

No further details are given. The ‘cursory attempts’ on an unknown number of mailers, which may have been Mailer 2, 3 or both, seem to have been a side project by DMSL’s expert and solicitor. No photographs were taken of what they did or how it turned out.

The results of the repeat experiments do not enable me to reach a conclusion as to whether opening Mailers 2 or 3 results in disruption in the base material, i.e. whether there is distortion of the base material such as to indicate that the mailers have been opened, after an attempt has been made to smooth the base material back into its unopened appearance. The burden rests on Everseal to prove infringement and it has not done so in relation to Mailers 2 and 3. I have to say that I have limited sympathy for Everseal. Its initial stance was that it wanted to conduct its own experiments, then it decided not to. Having changed its mind again at the last minute, Everseal was exceptionally given the opportunity not just to watch required repeats of DMSL’s experiments, but also to suggest variations which might have proved something. The opportunity was not taken.

DMSL alleges that the Patent is invalid for both lack of novelty and lack of inventive step having regard to the following three items of prior art and common general knowledge:

Everseal admitted that the Viking Mailer had been made available to the public in this country before the priority date, though only for a period of about 3 months in 1995. Its case was that the Viking Mailer did not anticipate claim 1 of the Patent because the Viking Mailer had not been shown (a) to have an irreversible seal or (b) to self-seal under a pressure of 500 kPa or less. It was not disputed that if it had those features, the invention claimed in claim 1 of the Patent was both disclosed and enabled by the marketing of the Viking Mailer.

No sample of the Viking Mailer was in court. DMSL relied on the evidence of Mr Shipley. When the Viking Mailer was on the market in this country in 1995 Mr Shipley was Senior Products Manager at Viking Direct and had been so for three years. His area of responsibility was envelopes and similar products. In his witness statement he said he recalled the Viking Mailer, which he called the ‘LBF Product’ after the company that supplied it to Viking Direct, Laser Business Forms Limited:

“9.

The adhesive used on the LBF Product was the sort of adhesive which would bond to itself but not to surfaces which did not have the adhesive on them. If adhesive coated onto one surface was contacted with the adhesive coated on another surface, and they were pressed together, they would bond firmly to each other.

10.

I handled self sealing envelopes at the time. There were two types of self sealing envelopes that Viking sold at that time. Envelopes with release strips covering a sticky adhesive and those with an adhesive which would bond to itself but would not stick to other surfaces such as other bits of paper. The LBF Product was of that description – the envelopes without a release strip. The adhesive was dry to the touch – at least if you had dry fingers. You needed both parts. The adhesive went on three sides of each part. With pressure the adhesive bonded to itself so that, as I explained above, it would seal the mailer closed. It only needed finger pressure to seal the LBF Product closed.

…

13.

In relation to opening the LBF Product I would have tried everything possible to try to open it up to and including a letter opener to push between the sheets to see how safe the seal was. The seal was more than adequate. If you tried to pull the parts apart you would end up by tearing it. You might have been able to peel apart a corner, but when you went on you would end up by tearing it.”

Despite Mr Shipley’s use of tense in paragraph 13 of his witness statement, on a fair reading I think he means that he did try to open the Viking Mailer after sealing. There can be no doubt that the seal in the Viking Mailer was irreversible because opening the mailer resulted in tearing it. Ms Pickard did not challenge what Mr Shipley said in paragraph 13. She focussed her cross-examination on whether the adhesive in Viking Mailer was self-seal. Mr Shipley’s response to being challenged on this was that he was clear that the Viking Mailer had been self-seal because it had impressed him as the first self-seal laser-compatible mailer he was presented with.

In argument Ms Pickard made four points. The first was that it was not clear on the correspondence and other documentary evidence that the Viking Mailer was self-seal, as opposed to ‘lick and stick’.

On 1 November 1994 Stephen Black of Abacus Laser Print wrote to Brian Powell of Viking Direct offering ‘an exciting new development in paper mailing systems’ which had been ‘after many months of testing’ on laser photocopying machines had been ‘successfully developed’. It is clear from the letter and is common ground that this was a lick-and-stick mailer. There followed exchanges between Mr Black and Viking and further correspondence. Shortly after 1 November 1994 either Mr Black moved to Laser Business Forms Limited (“LBF”) or Abacus Laser Print changed its name. The lick-and-stick mailer was supplied by LBF to Viking Direct.

On 12 January 1995 there was a phone conversation between Mr Black and Mr Shipley. Mr Shipley’s evidence was that he had said to Mr Black that he wanted a mailer with a contact adhesive and did not know why LBF had only offered a lick-and-stick mailer. This is consistent with a letter from Mr Black to Mr Shipley, also of 12 January 1995, in which he says that LBF had considered self-adhesive mailers:

“(ii)

Self-adhesive strips, instead of laser-compatible gum was an avenue we had explored. However, the additional expense of such strips, added to the perforating and print costs, made the product very expensive in our opinion.”

This suggests that an alternative self-seal mailer was available, but it does not spell out what sort of adhesive the mailer used, except that unlike the remoist adhesive, it was not laser compatible.

Then a further alternative product, namely the ‘V-fold Readymade Mailer’ was offered by LBF some time in January. On 3 February 1995 Mr Black wrote to Mr Shipley at Viking Direct:

“Many thanks for your fax dated 1st February 1995, in connection with our V-fold Readymade Mailers.

I am delighted that you have decided to include the product in your next two catalogues May to December.

…

I am extremely confident that now we have upgraded the mailers to laser-compatible finger-seal (self-seal), instead of traditional moisten gum, the mailers will have an even greater appeal.

I enclose a copy letter from our manufacturers of this product, Moore Paragon. The letter confirms that the self-seal pressure glue has been approved by no lesser authority than the Rank Xerox organisation.”

The letter from Mr Black confirms that the new mailers being offered to Viking Direct used an adhesive which could be self-sealed by finger pressure and which was compatible with laser printers. The letter does not state that this was a dry contact adhesive, as opposed to a tacky adhesive. But Mr Shipley was clear, and I accept, that the Viking Mailer used a contact adhesive, which would rule out the tacky ‘peel-and-stick’ variety. It was not in any event suggested to Mr Shipley that the adhesive was ‘peel-and-stick’.

These new mailers, marketed by Viking Direct from April 1995, were not a success. A letter dated 19 July 1995 from Mr Black of LBF to Viking Direct, by this time for the attention of Lee Winder, included this:

“Further to our telephone conversation this morning, I would like to confirm the following points in connection with One-Piece Mailers Ref.P25LBF2BL, prior to a meeting at your offices.

i.

It is plainly obvious that the mailers in their present format are not selling in the quantities that either of us are happy with. I think you said approximately 200 or 300 from Leicester and a further 50 or 100 from London. This is not very encouraging after three months and I think maybe this is because they are too expensive.”

Mr Black went on to suggest replacing the contact adhesive with remoist gum. He thought this would cause little complaint because the mailer was largely sold for return mail, so that the party sealing the mailer for return would only have one mailer to seal. He also said this:

“The remoist gum will reduce our gluing costs by 75%, as self-adhesive glue is very expensive to apply”.

Mr Shipley stated that after the 3 month experiment selling mailers with contact adhesive that could be self-sealed under finger pressure, Viking Direct went back to lick-and-stick mailers. The documents are fully consistent with Mr Shipley’s account in this regard. I accept this evidence.

Ms Pickard’s second point was that Mr Shipley freely admitted that he could remember little of the letters and phone calls surrounding the supply of the Viking Mailer by LBF. Ms Pickard submitted that if could to remember those, his recollection regarding the nature of the Viking Mailer was suspect. I don’t accept that. It seems to me entirely possible that letters and phone calls have faded from Mr Shipley’s memory in 20 years but his memory of a product that was new and of particular interest to him has not.

Ms Pickard’s third argument in this context was that the Viking Mailer could not have had the adhesive characteristics that Mr Shipley claimed for it because if it had, the Viking Mailer would have been a huge commercial success. I do not agree. The correspondence shows that the Viking Mailer was a commercial failure in 1995 as it was too expensive, apparently because of the cost of applying an adhesive of that type to the mailer. It may be that 20 years later mailers of this type are successful on the market. All that can be inferred is that the technological advances have made them cheaper to make, or market demand has changed sufficiently to accommodate the higher cost, or both. The impression I have is that a commercial ugly duckling in 1995 has, for one reason or another, over 20 years turned into to a profitable swan.

Finally Ms Pickard directed my attention to what HH Judge Fysh QC said in Kavanagh Balloons Pty Ltd v Cameron Balloons Ltd [2004] RPC 5, at [51] to [58] on the standard of proof. Judge Fysh summarised the position in this way at [58]:

“In summary, I am prepared to assess the evidence relating to prior use on a flexible and proportionate basis within the overall requirement of proof on the burden of probabilities – but no more.”

I do not at all dissent from that. Applying that approach I find that claim 1 of the Patent lacks novelty over the Viking Mailer.

Mr Caton’s evidence was that natural rubber latex adhesives stabilised with ammonia were well known and that in his view it was more likely than not that the Viking Mailer used such an adhesive. Mr Hill pointed out that this had not been challenged and submitted that in consequence claim 7 must also lack novelty over the Viking Mailer.

As Judge Fysh indicated in Kavanagh Balloons, the overall assessment of an alleged prior use is to be conducted according to the balance of probabilities. But there are particular considerations that apply in relation to an allegation of lack of novelty. In SmithKline Beecham Plc’s (Paroxetine Methanesulfonate) Patent [2005] UKHL 59; [2006] RPC 10, Lord Hoffmann, with whom the rest of the House agreed, considered observations of Lord Westbury L.C. in Hill v Evans (1862) 31 L.J. Ch (NS) 457 at 463 and those of the Court of Appeal in General Tire and Rubber Co v Firestone Tyre and Rubber Co Ltd [1972] R.P.C. 457, at 485-486 and said this:

“[22] If I may summarise the effect of these two well-known statements, the matter relied upon as prior art must disclose subject-matter which, if performed, would necessarily result in an infringement of the patent. That may be because the prior art discloses the same invention. In that case there will be no question that performance of the earlier invention would infringe and usually it will be apparent to someone who is aware of both the prior art and the patent that it will do so. But patent infringement does not require that one should be aware that one is infringing: “whether or not a person is working [an] … invention is an objective fact independent of what he knows or thinks about what he is doing”: Merrell Dow Pharmaceuticals Inc v H N Norton & Co Ltd [1996] R.P.C. 76, 90. It follows that, whether or not it would be apparent to anyone at the time, whenever subject-matter described in the prior disclosure is capable of being performed and is such that, if performed, it must result in the patent being infringed, the disclosure condition is satisfied. The flag has been planted, even though the author or maker of the prior art was not aware that he was doing so.

[23] Thus, in Merrell Dow, the ingestion of terfenadine by hay-fever sufferers, which was the subject of prior disclosure, necessarily entailed the making of the patented acid metabolite in their livers. It was therefore an anticipation of the acid metabolite, even though no one was aware that it was being made or even that it existed. But the infringement must be not merely a possible or even likely consequence of performing the invention disclosed by the prior disclosure. It must be necessarily entailed. If there is more than one possible consequence, one cannot say that performing the disclosed invention will infringe. The flag has not been planted on the patented invention, although a person performing the invention disclosed by the prior art may carry it there by accident or (if he is aware of the patented invention) by design.

Lord Hoffmann there emphasised that if it is alleged that carrying out the teaching of certain prior art would lead to the performance of the claimed invention, it must inevitably do so if the claimed invention is to lack novelty. I think this casts light on the nature of the evidence required to establish that a prior use deprives an invention of novelty.

Where lack of novelty turns on whether an alleged prior use had particular features, it is sufficient to adduce evidence which proves, on the balance of probabilities, facts which establish that the prior use had those features. By contrast where the court is invited to infer that the prior use had one or more features on the basis of primary facts proved, the claimed invention will lack novelty only if the inference is an inevitable one. No matter how likely an inference it is, if the primary facts allow for the possibility of an alternative inference the invention will not lack novelty.

In the present case I am satisfied that sufficient facts have been proved, on the balance of probabilities, to establish that claim 1 of the Patent lacks novelty. I am invited to reach the same conclusion in relation to claim 7 on the unchallenged evidence of Mr Caton that it was likely that the adhesive in the Viking mailer was a natural rubber latex adhesive stabilised with ammonia. This is in effect a submission that taking into account all relevant circumstances relating to adhesives used in 1995 it is a likely inference that the adhesive was a natural rubber latex adhesive stabilised with ammonia. That in my view is not enough to establish lack of novelty and I conclude that claim 7 does not lack novelty over the Viking Mailer.

Faltin is a US patent published in 1969 which claims a flat sheet of material folded in a particular way such that it forms an envelope for use as a mailer. It is the sort of mailer that can be inserted into a Sunday supplement and used by readers to respond to an offer.

As in relation to the other prior art, Everseal argued that there is no disclosure in Faltin either that the mailer self-seals irreversibly or that the mailer self-sealed under pressure of 500kPa or less. It is enough to consider the former. DMSL relied on the following passage at column 6, lines 9-17 (here leaving out the number references):

“In the event that the cement employed for the sealing stripes…is of the contact type, such as a dry pressure-sensitive adhesive, it is then preferred that the stripes…continue preferably entirely along the opposite side edges of the piece so that when the panels…are folded upon each other, the engagement of said stripes of contact adhesive upon each other will immediately and permanently seal the same.”

Mr Hill emphasised the word ‘permanently’ in that passage and said that it can only be construed to mean ‘irreversibly’. I do not think that follows. I cannot rule out the possibility that ‘permanently’ means that the seal will survive passage through the post but can be opened without disruption to either the adhesive structure or alternatively the base material. I find that the Patent does not lack novelty over Faltin.

Johnsen is a US patent published in 1974. It claims a mailer which can be rapidly printed and processed for mailing through a collating machine. DMSL accepts that there is no explicit disclosure of an irreversible seal but relies on the evidence of Mr Caton that it is a reasonable inference. For reasons analogous to those discussed above, I do not accept that this is sufficient. The Patent does not lack novelty over Johnsen.

As I have mentioned, in relation to all three items of prior art, Ms Pickard argued that the elements missing from their disclosure were (a) that the seal was irreversible and (b) that the mailer self-sealed under pressure of 500 kPa or less.

It was not in dispute that the skilled team would have been aware that adhesives were available with characteristics to satisfy those two related features of claim 1. Such adhesives were used at the priority date for self-seal envelopes. Ms Pickard’s argument was that there was a general prejudice in the minds of those skilled in the art which would have caused the skilled team to reject the use of such adhesives on mailers to the extent that it would not have been obvious to try them with a reasonable expectation of success.

In fact there were, Ms Pickard argued, two prejudices. First, the skilled team would have expected the relevant adhesives to be damaged if used in laser printers because of the heat to which the adhesive would be exposed. This was to be contrasted with envelopes, where the flap would be folded such as to protect the adhesive from direct contact with the hot rollers. Secondly, there was a prejudice against using such adhesives in ink-jet printers. The paper from which mailers were made destined for printing in an ink-jet printer was of a special type. It had to be shiny and non-absorbent. It was believed that the adhesive could not form a sufficient bond with such paper to create an irreversible seal. Ms Pickard relied on the evidence of Mr Palmer.

As Mr Hill pointed out, the short answer to this was that it was clear from the specification of the Patent that claim 1 encompassed mailers which were filled in using a typewriter or by hand (see, for example, page 1, lines 11-16). No technical prejudice was suggested by Everseal that would deter the skilled team from using an adhesive which self-sealed under a pressure of 500 kPa or less to create an irreversible seal, where it was intended that the mailer should be completed by hand or by using a typewriter.

Ms Pickard also relied on an argument of long-felt want. Assuming the long-felt want was there in the mailer industry, the correspondence discussed above indicates that there was no technical barrier to making the invention in July 1998 (here assuming that it had not already been done). The barrier was a commercial one. In my view it would have been known to the skilled team that the relevant adhesives could be used for mailers, but the cost was thought too prohibitive to create a commercially successful product.

I find that the invention claimed in claim 1 of the Patent lacks inventive step over Faltin and Johnsen, and over the Viking Mailer if it did not anticipate the invention.

The argument of an alleged prejudice made more sense in relation to claim 7, which is dependent on claim 6 and thus restricted to mailers which are laser-printable. The issue was whether the skilled team would have contemplated the use of a contact adhesive which self-sealed irreversibly under a pressure of 500 kPa or less for mailers to be printed in a laser printer. Adhesives having those qualities (leaving aside their suitability for laser printers), especially natural rubber latex adhesives stabilised with ammonia, were known to the skilled team. Their disadvantages of cost referred to above are not relevant.

Mr Caton’s evidence in his witness statement was that if in July 1998 the adhesives member of the skilled team had been asked for an adhesive with the required properties and which also had the ability to withstand the rigours of a laser printer, it would have been a matter of tweaking known formulations and trying them out in a laser printer. He said that the skilled person would have expected to find a suitable formulation without difficulty. He maintained this evidence in cross-examination. Mr Palmer, in cross-examination anyway, gave similar evidence. He said that the task of finding a suitable adhesive in July 1998 for the purpose described would have been a ‘bread and butter’ task for the adhesives skilled person. Lest there be doubt what he meant by that, he said that it would have been a routine matter to find such an adhesive and that he would have expected the skilled person to succeed. He also accepted that adhesives worth trying would commonly have been natural latex rubber adhesives stabilised with ammonia.

On that evidence I have no doubt that claim 7 lacks inventive step.

In Teva UK Limited v Leo Pharma A/S [2014] EWHC 3096 (Pat), Birss J, having found that the patent in suit was invalid for lack of inventive step, turned to consider the argument that the patent was also invalid for added matter. He said this:

“[103] TEVA submitted that all the claims currently sought by LEO were bad for added matter. It was an independent ground of invalidity, however I do not propose to deal with it because it does not depend on any court (at this level or on appeal) making findings of fact by resolving disputed evidence. It is primarily a matter of construction and is therefore something an appellate court would be able to resolve if necessary.”

The procedural economy adopted there is particularly suited to the IPEC, where appropriate. I think it is appropriate here and I say nothing about the arguments on added matter.

The arguments of lack of good faith are made pursuant to s.62(3)(b) and (c) of the Act, as amended :

“(3)

Where an amendment of the specification of a patent has been allowed under any provisions of this Act, the court or the comptroller shall, when awarding damages or making an order for an account of profits in proceedings for an infringement of the patent committed before the decision to allow the amendment, take into account the following –

…

(b)

whether the specification of the patent as published was framed in good faith and with reasonable skill and knowledge,

(c)

whether the proceedings are brought in good faith.”

The same consideration of procedural economy applies. The two arguments of lack of good faith advanced by DMSL do not arise on the findings I have made above. They would arise if those findings are reversed on appeal, but only at the hearing of an inquiry as to damages or an account of profits which would follow the appeal and be heard in this court. The parties have already elected that the issue of joint tortfeasance should be heard at the inquiry or account if there is one. I therefore take this no further.

If the Patent were valid, Mailer 1 would infringe claim 1 but not claim 7. Mailers 2 and 3 would infringe neither claim 1 nor claim 7. The Patent is invalid for lack of novelty over the Viking Mailer and for lack of inventive step over Faltin and Johnsen.