Zeno Corp (Formerly Known As Tyrell Inc) & Anor v BSM-Bionic Solutions Management GmbH & Anor

In September 2007 Boots plc began to sell Zeno, a device manufactured by Tyrell Inc. In February 2008 patent attorneys acting on behalf of Riemser Arzneimittel AG wrote to Boots, drawing attention to Riemser’s patent EP (UK) No. 1 231 875, and expressing the view that Zeno had adopted the same technical solution. The invention claimed in the patent is a hand-held unit for the treatment of insect stings and insect bites. But Zeno is not used for that purpose. It is used for the treatment of acne; and the instruction leaflet that comes with it says in terms that it should not be used for insect or spider bites or stings. Boots stopped ordering Zeno, although they were later persuaded to reorder. This action is a claim (technically a counterclaim) by Riemser for infringement of its patent. Predictably, Tyrell say that the patent is invalid; and that anyway they do not infringe it. They also say that the letter from Riemser’s patent attorneys amounted to a threat of infringement proceedings.

Tyrell’s medical expert was Dr Ronald Behrens. He is a consultant in Tropical and Travel Medicine at the Hospital for Tropical Diseases. He directs the Hospital for Tropical Disease's Travel Clinic; and is also Senior Lecturer at the Department of Infectious and Tropical Diseases at the London School of Hygiene and Tropical Medicine, a postgraduate school in the University of London. His research interests include malaria and its prevention, particularly on studies on identifying measures that travellers should take to avoid malaria, and also on the effectiveness and toxicity of malaria prophylactic drugs. He has been involved in evaluating and assessing the effectiveness of bite prevention strategies and products available for bite prevention. He has also conducted studies on imported infectious diseases including malaria, hepatitis A and tuberculosis. He has been closely involved in the diagnosis and treatment of insect bites and diseases related to insect bites such as leishmaniasis and dengue fever.

Riemser’s medical expert was Professor Peter Friedmann. He is Emeritus Professor of Dermatology at the University of Southampton. Since 1998 his main areas of research have been the immune mechanisms underlying allergic reactions to chemicals experienced by skin contact or as therapeutic medicinal drugs. He has continued to work on the environmental impact on the skin, in particular the mechanisms of the effects of ultraviolet light and noxious environmental chemicals on the skin.

Dr Behrens’ view was that the patent in suit was addressed to a team of people including those with experience in the design and manufacture of medical devices together with those with medical or first aid experience in the treatment of insect bites and stings. The team would also have included an engineer capable of actually making the device that the patent in suit describes. Professor Friedmann’s view was that it was addressed to researchers and doctors with practical knowledge and experience of the physiology of the skin and the treatment of skin conditions. This group of people would include, but not be limited to, researchers and doctors with a particular interest in the physiological reactions to, and the treatment of, insect bites and stings. However, this specific topic is not routinely studied by any one, well-defined group of specialists, but rather overlaps the areas of interest and experience of different groups of researchers and doctors, in particular research dermatologists and allergologists. The patent in suit would also be of interest to manufacturers of electrical healthcare devices, but they would have sought the advice of a dermatologist or allergologist.

In the end, this minor disagreement did not matter. Both experts agreed that the addressee would be a team consisting of a medically qualified person and an engineer. The first aid experience to which Dr Behrens referred was not the sort of first-aider trained to deal with minor workplace accidents or a boy scout, but a GP or similar; and Professor Friedmann accepted that a GP would be adequately qualified to read and understand the patent in suit. Moreover, despite their minor disagreement on the makeup of the team, both experts were agreed on the common general knowledge that such team would possess.

Generally insect bites and stings cause distress and discomfort rather than danger. In most cases they can be self-treated in the field; but in other events the consequences and complications are much more significant and medical expertise will be required. The patent in suit is concerned with treatment in the field.

Venomous insects attack as a defence mechanism injecting toxic venom through their stings. Because a sting is part of an insect’s defence mechanism, it is meant to hurt. Stings hurt because they contain a small amount of venom that triggers a histamine response resulting in swelling, burning and itching. In most patients, this is the extent of the response. In a small number of cases the victim may suffer a more severe reaction, in which case urgent medical advice should be sought as the victim may require adrenaline injections. The current standard treatment for stings is as follows. First, the stinger should be removed using the edge of a dull knife or a fingernail. The wound should be cleaned and treated with a topical (or oral) analgesic together with an antiseptic cream. The application of ice or a cold wet compress can help reduce itching and swelling. Some individuals benefit from oral anti-histamine medication.

In contrast to stinging insects, biting insects use their bite as a means to feed. Their aim is to go unnoticed during the feeding process, and therefore, insect bites are (generally speaking) not painful at the time of the bite itself. When insects bite, they inject saliva into the skin. It is the constituent elements of insect saliva (e.g. anticoagulants, amines, peptides, enzymes, etc.) that cause the inflammatory and allergic reactions to insect bites, in a similar way to the venoms of stinging insects.

Itching is the main symptom associated with insect bites. Topical antihistamines can alleviate itching. The bite should also be cleaned and treated with antiseptic. If there is significant pain, this can be alleviated with oral analgesics. Any systemic reaction including facial swelling, shortness of breath or wheezing, difficulty swallowing, light-headedness or fainting should be managed by a doctor urgently. Systemic treatment with adrenaline and steroids are the standard management of anaphylaxis.

During biting and stinging the insect is not usually observed and/or recognised and so when patients present with symptoms relating to a bite, the causative insect is usually unknown. Accordingly, treatment is generally symptom dependent rather than relating to the insect except where there is a clear syndrome such as bee or wasp sting or acute anaphylaxis.

Thermolabile poisons were not part of the common general knowledge of the skilled person as at 1999. Even now Professor Friedmann was only able to identify one such poison, phospholipase (although he did not know what insect injected phospholipase) and accepted that he did not even have this limited knowledge as at 1999. Nor would the skilled person know the actual temperatures at which the poisons are denatured.

Thermal burns are injuries that result from exposing the skin to heat sufficient to cause damage and death of cells and tissues. The effects of the heat will depend upon the intensity (temperature), duration of exposure, type of heat source and its contact with the skin (whether wet or dry), as well as the thickness of the skin and the surface area exposed. Delivery of such a heat "insult" to the skin will cause pain which may vary from tolerable to extreme. Depending on the depth to which the skin tissues are damaged, thermal burns may have a variety of appearances and consequences.

Contact with hot water at 45^oCcauses minimal damage that results in redness (erythema), and tissue swelling. Water between 50°Cand 55°C can cause blistering and loss of the surface layers of skin, depending on the duration of contact. Dry contact, such as with metal or air, transfers heat into the skin much less efficiently, so higher temperatures can be tolerated before the tissues are damaged. However the precise temperature and duration of exposure to dry heat sufficient to cause damage to the skin was neither part of common general knowledge nor readily available in the literature.

The medical community was also aware of folkloric methods of treating stings and bites. These included "bicarb for bees and vinegar for wasps". They also included hot baths to reduce itching.

However these “remedies” have no proven scientific basis. Chinese culture had a long tradition of using heat to treat a vast range of symptoms and conditions but, again, these practices were (and are) not generally accepted as scientifically sound by Western medicine. In many cases, if inflamed skin is heated up to temperatures as would typically be used in a hot bath (e.g. up to about 40°C - 45°C), then the inflammation can be exacerbated because of the increased blood-flow to the inflamed area. As at 1999 there was no theory for the treatment of stings and bites by the application of heat that was generally accepted in the medical world. On the contrary, the classical response to inflammation was (and is) the application of cold and soothing material such as a flannel or ice to relieve swelling and discomfort. Local application of heat is in direct contrast to this standard of practice.

Thus the view of the western medical community was that it was likely that these remedies work (if at all) as placebos. However, the placebo effect is not to be underestimated, especially in the treatment of itch, the most common symptom in response to an insect bite. Itch is as much a sensation as a physical discomfort and so is particularly prone to psychosomatic manipulation.

The patent in suit begins by saying that:

Having considered methods of preventing stings and bites in the first place (which are not wholly effective) it then goes on to describe features of the prior art. It acknowledges devices that work by the application of heat, including one device (referred to in this case as Lombal) which it acknowledges as having all the integers of the pre-characterising part of claim 1. The disadvantage of the prior art is that:

It then sets out the object of the invention as follows:

The patent in suit goes on to describe the device. In essence it consists of a hotplate and a control which regulates both the temperature of the hotplate and the time for which it remains heated. By activating a key, the device begins a “heating up phase”. During this phase the hotplate heats up to a specified maximum temperature. Once the hotplate has reached the required temperature, a second phase called the “heating phase” begins; and the time control is triggered. This control consists of both a time regulator and a temperature regulator. During the specified duration of the heating phase, which corresponds to the duration of treatment, the temperature regulator ensures the maintenance of the maximum temperature and, at the same time, prevents it from being exceeded. After the expiry of the heating phase, the heating operation is terminated; and the temperature of the hotplate returns to the ambient temperature.

The specification continues:

The patent in suit goes on to give examples of different temperature and time curves. Temperatures are specified in multiples of 5^o C. Time is measured in seconds to one or two decimal points. The patent in suit says:

It points out that:

Having described the device, the patent in suit sets out the claims:

A number of integers of the claim have disputed constructions. There is, however, no dispute about the principles of construction that I must apply. The principles were summarised by Jacob LJ in Mayne Pharma Pty Ltd v Pharmacia Italia SPA[2005] EWCA Civ 137 and refined by Pumfrey J in Halliburton Energy Services Inc v Smith International (North Sea) Ltd[2005] EWHC 1623 (Pat) following their general approval by the House of Lords in Kirin-Amgen v Hoechst Marion Roussel[2005] RPC 9. An abbreviated version of them is as follows:

The first overarching principle is that contained in Article 69 of the European Patent Convention;

Article 69 says that the extent of protection is determined by the terms of the claims. It goes on to say that the description and drawings shall be used to interpret the claims. In short the claims are to be construed in context.

It follows that the claims are to be construed purposively—the inventor's purpose being ascertained from the description and drawings.

It further follows that the claims must not be construed as if they stood alone—the drawings and description only being used to resolve any ambiguity. Purpose is vital to the construction of claims.

When ascertaining the inventor's purpose, it must be remembered that he may have several purposes depending on the level of generality of his invention. Typically, for instance, an inventor may have one, generally more than one, specific embodiment as well as a generalised concept. But there is no presumption that the patentee necessarily intended the widest possible meaning consistent with his purpose be given to the words that he used: purpose and meaning are different.

Thus purpose is not the be-all and end-all. One is still at the end of the day concerned with the meaning of the language used. Hence the other extreme of the Protocol—a mere guideline—is also ruled out by Article 69 itself. It is the terms of the claims which delineate the patentee's territory.

It follows that if the patentee has included what is obviously a deliberate limitation in his claims, it must have a meaning. One cannot disregard obviously intentional elements.

It also follows that where a patentee has used a word or phrase which, acontextually, might have a particular meaning (narrow or wide) it does not necessarily have that meaning in context.

It further follows that there is no general "doctrine of equivalents."

On the other hand purposive construction can lead to the conclusion that a technically trivial or minor difference between an element of a claim and the corresponding element of the alleged infringement nonetheless falls within the meaning of the element when read purposively. This is not because there is a doctrine of equivalents: it is because that is the fair way to read the claim in context.

Finally purposive construction leads one to eschew the kind of meticulous verbal analysis which lawyers are too often tempted by their training to indulge.

The received wisdom is that the use of the word “for” in a patent claiming a product means that it covers any product that is “suitable for” the particular purpose specified in the claim. It was common ground that this was the case here. The origin of this principle of construction is, according to Mr Burkill, the decision of Parker J in Adhesive Dry Mounting Co Ltd v Trapp & Co (1910) 27 RPC 341. The patent in that case contained a process claim of mounting photographs etc on cardboard consisting of interposing between the two surfaces a thin layer of material capable of becoming adhesive under the action of heat. Another claim claimed:

The question was whether that claim claimed the pellicle itself or merely the use of the pellicle for the process claimed in the earlier claim. Parker J said:

That was the only reason he gave for that construction. Likewise in Coflexip SA v Stolt Comex Seaway MS Ltd [2000] IP & T 1332 a patent claimed both a process and a device “for operating the process according to one of the preceding claims”. It was argued that this limited the claim to a device when used for the claimed process. The Court of Appeal rejected that argument.Aldous LJ said:

As a question of construction of those particular patents these decisions are unexceptionable, because it will seldom be right to construe a claim so that it is entirely redundant. But it seems to me, with all respect, to be a slender foundation for the wider rule of construction applicable across the board that has been subsequently developed with no further explicit reasoning in any of the cases that have subsequently referred to or applied the supposed rule. Moreover, as Lord Hoffmann pointed out in Merrell Dow Pharmaceuticals Inc v H.N. Norton & Co Ltd[1996] R.P.C. 76, 92 this sits uneasily with the decision of the EPO Board of Appeal in MOBIL/Friction reducing additive Decision G02/88[1990] E.P.O.R. 73. Since a patent is a unilateral document, written in words of the patentee’s choice, one might also reasonably ask: if he meant “suitable for”, why did he not say it? In Folding Attic Stairs Ltd v The Loft Stairs Company Ltd[2009] EWHC 1221 (Pat) Mr Peter Prescott QC, sitting as a judge of the Patents Court, said:

Nevertheless in FNM Corporation Ltd v Drammock International Ltd [2009] EWHC 1294 (Pat) decided a few days later Arnold J considered the position in some detail including the decision of the Court of Appeal in Actavis UK Ltd v. Merck & Co Inc; and affirmed the “the principle that the word “for” in a patent claim means “suitable for””. So despite my own doubts, and in view of the common ground, I will assume that the emperor is clothed and apply the received wisdom that “for” a purpose means “suitable for” that purpose. In this case the specified purpose is the “local thermal treatment” of insect stings and bites.

However, that still leaves the question: if the manufacturer of a product does not design or intend it to be used for the specified purpose, how does one judge whether it is “suitable” for use for that purpose? Is it simply a question of whether something is capable of being used for a specified purpose? After all, Terrell is capable of being used as a doorstop or a paperweight; and a popular cartoon book of a few years ago was entitled “101 Uses for a Dead Cat”. Was it “suitable” for all those uses? Closer to home, some of the feedback relating to Riemser’s own product extolled the efficacy of a hot mug of tea or a lit cigarette end in applying heat to the site of insect bites. But are these “suitable” things to use?

Bühler AG v Satake UK Ltd[1997] R.P.C. 232 concerned a claim to “a roller mill for the milling of cereal”. Jacob J said:

This suggests that a device will be suitable for a specified purpose if it is capable of being used for that purpose without adaptation. On this test (which was apparently not disputed in the end) a hot mug of tea would be suitable for treating insect bites. The EPO’s Guidelines for Examination (April 2009 edition) which Arnold J quotes in FNM Corporation Ltd v Drammock International Ltd suggest a more nuanced test. They say (section C-III § 4.13):

The first sentence of this quotation appears to envisage that something may be unsuitable for the specified purpose even if it contains all the features of the claim, since that is put forward as an alternative to modification. Again, despite my doubts, I am content to proceed on the basis that something is suitable for a specified purpose if it is capable of being used for that purpose without modification.

Mr Vanhegan QC said that there were two possible constructions of the specified purpose. The first (narrow) construction was that the product had to be suitable for the treatment of bites and stings, in the sense of providing effective treatment by neutralising the thermolabile poison injected by the insect. The second (and wider) construction was that the product must be suitable for applying heat to the site of an insect bite or sting. He said that the narrow construction was the correct one.

Although the theory advanced in the specification is that the invention works by neutralising thermolabile poisons, the theory is, in the view of both medical experts, at best dubious. But, as Mr Burkill submitted, the theoretical underpinning does not form part of the claim itself, which is a claim to a product rather than to a process. Based on Terrell § 7-104 and Auchinloss v Agricultural & Veterinary Supplies[1999] RPC 397, 402 he submitted that as long as there was a “real effect” on the consequences or symptoms of insect bites and stings it did not matter what caused that effect. I agree with this, as long as the real effect in question is a beneficial one, otherwise it cannot realistically be called “treatment”.

I therefore accept that a device “for … treatment” must be capable of having some real beneficial effect on the symptoms experienced by one who has been bitten or stung by an insect, but I do not consider that it matters why it works (assuming that it does). This is a little narrower than Mr Vanhegan’s wide construction, but not as narrow as his narrow one.

Claim 1 refers to:

The question under this head is the precision with which those temperatures must be interpreted. Mr Vanhegan relies on the decision of Mr Peter Prescott QC, sitting as a judge of the Patents Court, in Auchinloss v Agricultural & Veterinary Supplies[1997] RPC 649 at 689-90 in which he said:

This part of the deputy judge’s judgment was not affected by the appeal. Mr Burkill, on the other hand relies on the decision of Aldous J in PLG Research Ltd v Ardon International Ltd[1993] FSR 197 in which the claim required a junction to have a thickness of “not less than 75 per cent” of the thickness of the mid-point of a strand passing through the junction. Aldous J said:

Terrell § 6-138 gives other examples where numerical limits have been interpreted with some flexibility, in particular by applying the scientific convention that numbers are given to the number of figures that are significant. Thus 10 will cover a range from 9.5 to 10.4; 10.1 will cover a range from 10.05 to 10.14 and so on. In the end I think that both sides agreed with the statement in Terrell:

It is plain that the temperatures are expressed as whole degrees (i.e. 65ºC rather than 65.0ºC). So it is not difficult to understand that a range between 64.5^oC and 65.4^oC would be encompassed in 65ºC. Mr Burkill points to two additional features of the specification. First he refers to the passage in which it says that the hotplate is heated to:

Mr Burkill argues that the stated tolerance applies to all values mentioned in claim 1. Thus 65^oC would encompass 68^oC. In fact the logic of this argument goes further. If both 65^oC and 3^oC are expressed to two significant figures, then 65^oC in the claim can encompass 68.4^oC. Second, he says, where the specification refers to illustrative figures, the temperatures are presented in multiples of 5^oC. On this basis, therefore, 65^oC can encompass 70^oC (or possibly 70.4^oC or even, if the 3^oC tolerance point is also right, 73.4^oC).

In evaluating this argument, it must be remembered that what the claim is talking about is applying heat to human skin. Moreover, it is talking about applying heat to human skin for a predetermined length of time. The minimum duration specified in the claim is 2 seconds, and the preferable minimum specified is 3 seconds. Professor Friedmann’s evidence was that if heat is applied to human skin at 65^oC a burn will be caused after half a second, and that at 65.49^oC a burn would be caused even more quickly. It follows that the application of heat at 68^oC would cause an almost instant burn; and if applied for the minimum specified period of 2 seconds the burn is likely to be serious. The application of heat at 70^oC would be extremely dangerous. I must also bear in mind that the precise combination of temperature and duration of exposure to heat sufficient to cause real damage was not part of common general knowledge. Nor was the method of treatment proposed by the patent in suit part of common general knowledge. Accordingly the skilled reader would not have had any “feel” for the effects of straying outside the explicit parameters of the claim. Thus the skilled reader would have been very cautious, since both experts agreed that safety would have been his paramount consideration. In those circumstances I do not consider that the skilled reader would read the specified temperatures as unimportant or imprecise. He would not understand that a maximum temperature of 65^oC could extend beyond 65.4^oC. What goes for the maximum temperature must also go for the minimum temperature. There are two additional points that reinforce this conclusion. First, the specification says:

If these temperatures are read with a tolerance of ± 3^oC then it would mean that the specification is saying that at 63^oC (60^oC + 3^oC) the heating should not exceed 5 seconds otherwise skin damage might occur; and at the same time is saying that at 62^oC (65^oC – 3^oC) the heating should not exceed 3.5 seconds otherwise skin damage might occur. This would be self-contradictory teaching; and given that the duration of heating is measured with an accuracy of half a second, it seems to me to be unlikely that the skilled reader would interpret this teaching as loosely as Mr Burkill suggests.

Second, claim 6 claims:

If the tolerance of ± 3°C is already incorporated into claim 1, then claim 6 is entirely pointless. Moreover the fact that the tolerance is expressed as ± 3°C clearly shows that the patentee was being more precise than the separation of temperatures by multiples of 5^oC.

I hold, therefore, that the temperatures given in the claim are to be read as accurate to two significant figures, with the consequence that the minimum temperature specified in claim 1 is to be read as 49.5^oC and the maximum temperature is to be read as 65.4^oC (or 49.50 and 65.49 respectively).

Claim 1 refers to:

The question under this head is whether 12 seconds is the maximum duration of the heating phase.

Mr Vanhegan starts with the object of the invention. This has twin goals: first to deliver the amount of heat necessary to neutralise poisons; and second to achieve that goal without causing skin irritations. Accordingly, precise control over both time and temperature will be necessary to achieve these goals. If the temperature is precisely controlled, but the time of exposure to heat is not, then the user of the device suffers an increasing risk of burns the longer he uses the device. This is reinforced by a passage in the specification that says:

Unless both temperature and duration are strictly controlled, an exact introduction of heat is not possible; and without such exactness damage to the skin will certainly be feared. Moreover, when the specification and the claims deal in times, they do so with precision. Thus, for instance, the defect in the prior art to which the specification draws attention is that:

Likewise claim 4 speaks of maintaining a temperature for a duration of 5.5 seconds, and claim 5 a duration of 3.25 seconds. Where the patentee descends to quarters of seconds it is clear that precision is intended.

Mr Burkill on the other hand says that the patent teaches that the duration above which damage will be caused to the skin depends on the temperature. It follows therefore that at lower temperatures the duration of the application of heat can be longer than the claimed range. The skilled reader would thus understand that the claim meant “at least about 2 to 12 seconds” for efficacy but he would appreciate that it could be longer, subject to not compromising safety.

I prefer Mr Vanhegan’s argument. If Mr Burkill is right, then “ranging from 2 to 12 seconds” means the same as “at least 2 seconds”. Moreover, the same considerations that would have led the skilled reader to have been cautious about straying outside the temperature ranges referred to in the claim would have made him equally cautious about straying outside the durations given in the claim. Mr Burkill also relied on passages in the evidence in which the experts said that a duration of application at the maximum temperature for longer than 12 seconds inevitably maintains the maximum temperature for 12 seconds. In the first place this is a question of construction for the court, rather than a matter for the experts. Second, the claim does not speak of a period of 2 to 12 seconds. Rather, it speaks of a “time interval” of 2 to 12 seconds. The ordinary meaning of an “interval” is that it intervenes between two other things. In other words it has a beginning and an end. In addition the specified time interval is one “ranging from” 2 to 12 seconds, which again shows that the period has both a beginning and an end. In my judgment Mr Burkill’s construction involves a drastic rewriting of one of the integers of the claim. In the context of the patent in suit I hold that a time interval of 2 to 12 seconds means a period that is not less than 2 seconds and not more than 12.

Claim 1 refers to:

Mr Burkill says that the claim uses the words “heatable” and “maintainable” in order to make it clear that this is a product claim. If it had used the words “heated” and “maintained” then there would only be an infringement when an otherwise infringing device was switched on. I do not think that Mr Vanhegan seriously dissented from this. In essence his submission was that “heatable” and “maintainable” meant that when in use the device was “heated to” the maximum temperature and “maintained at” that temperature for the designated period. This coincides with my own understanding of this integer.

Mr Vanhegan potentially had a point about added matter; but in the light of my construction of the claim it does not arise.

As I have said, the Zeno device is marketed as a treatment for acne. It is a hand held, battery operated device designed to apply heat to an acne lesion at a controlled temperature for a metered duration of treatment. The device is manufactured for a US company and marketed extensively in the US. One consequence of this is that temperatures are measured in degrees Fahrenheit rather than Celsius. I have used the Celsius equivalents. The way the device works (so far as relevant to the question of infringement) is broadly as follows. It is activated by pressing a power button. After about a minute a green flashing light is seen. The green flashing light is pressed to initiate treatment. The metal treatment tip is placed on the acne spot and held there for the 2 ½ minute treatment cycle.

The function of the metal treatment tip is to act as a hotplate. It is heated by heat producing resistors powered by the batteries; and a thermistor measures the temperature of the metal treatment tip to within 0.28^oC. Unless the device fails the maximum temperature of the metal treatment tip during each of the treatment cycles is 48.33^oC. The temperature of the metal treatment tip at the time the green light starts flashing is designed to be approximately 46.67^oC. After the green flashing light is pressed the temperature of the metal treatment tip gradually rises during the first 60 seconds of the treatment cycle. After the first 60 seconds of the treatment cycle the power to the heat producing resistor is interrupted for a short period so as to reduce the temperature of the metal treatment tip by 0.56^oC. When the heat supply is resumed the temperature of the metal treatment tip initially rises rapidly and then maintains a more or less constant temperature for the remaining 90 seconds of the 2 ½ minute treatment cycle. The temperature to which the metal treatment tip rises (and at which it remains more or less constant) is approximately 0.28^oC lower than the maximum temperature during the first 60 seconds of the treatment cycle (i.e. approximately 46.4^oC). During the 10 second interval between the end of the first treatment cycle and the start of the second, the temperature of the metal treatment tip rises by about 0.56^oC.

Thus, during the second treatment cycle the temperature of the metal treatment tip is higher than in the first treatment cycle, both at the start of the cycle and at any corresponding point in the cycle. However, the second treatment cycle follows the same pattern as the first. A third treatment cycle follows the second. Again, during the third treatment cycle the temperature of the metal treatment tip is slightly higher than the temperature attained in the second treatment cycle.

The rather imprecise language of the product description was supplemented by temperature graphs which were more precisely measured and drawn. The Zeno device is set so that the temperature of the metal treatment tip cannot exceed 119^oF (48.3^oC). However, as measured by Mr Yee there were occasions on which this limit was exceeded (albeit by a very small margin). Typically the device operated at temperatures between 47.5^oC and 48.3^oC.

On the basis of my construction of the claim, the Zeno device maintains its temperature for longer than 12 seconds and thus falls outside the claim. It also operates at too low a temperature to fall within the claim.

Mr Vanhegan also submitted that it had not been demonstrated that at the temperatures at which the Zeno device operated it had any beneficial effect at all on the consequences or symptoms of insect stings or bites. On the contrary the evidence was that the application of wet heat (i.e. a hot bath) at 40^oC to 45^oC can exacerbate an inflammation. The Zeno device operates at only two or three degrees above that bracket. Moreover Professor Friedmann said that the application of dry heat rather than wet heat was less efficient at transferring heat to the skin. So it cannot be assumed that the application of dry heat at a temperature of two or three degrees above the range of temperatures at which wet heat can exacerbate symptoms would have any different effect. Mr Burkill accepted that the evidence that the Zeno device had any beneficial effect on the consequences or symptoms of insect stings or bites was thin. In fact it was non-existent. Neither expert had addressed the question. The best Mr Burkill could do was to show that one of the pieces of prior art was marketed as an “itch stopper” on the basis that the user could select a temperature of operation which could be as low as 45^oC and as high as 51.5^oC. But there was no evidence that the prior art device worked at that low temperature. In effect Mr Burkill invited me to infer that the Zeno device would have a beneficial effect at its operating temperature. In view of the relative lack of knowledge about the precise temperatures at which the application of heat can produce a beneficial effect (and in view of the experts’ scepticism about the whole theory on which the patent in suit is based) I think it would be foolhardy to draw any such inference. The fact is that Professor Friedmann did not himself suggest that the Zeno device would have any beneficial effect on the consequences or symptoms of insect stings or bites; and there was no other positive evidence to that effect. It is for Riemser to discharge the burden of proving infringement; and I hold that they have failed to do so. It has not been proved that the Zeno device is capable of treating the consequences or symptoms of insect stings or bites.

Accordingly the Zeno device does not infringe.

There was only one piece of prior art relied on as anticipating the invention claimed by the patent in suit: a patent application (CN 1,113,747A) made by Dr Li in 1995 (“Li”). The test for anticipation is whether the prior inventor’s publication contains a clear description of, or clear instructions to do or make something that would infringe the patentee’s claim if carried out after the grant of the patentee’s patent. To anticipate the patentee’s claim the prior publication must contain clear and unmistakeable directions to do what the patentee claims to have invented: General Tire and Rubber Co v Firestone Tyre and Rubber Co Ltd [1972] RPC 457.

The principal issue arising in relation to Li was whether it disclosed a timer. As I have said, Li was a patent application. The original was in Chinese and we all worked from a translation. The quality of the English was not of the highest, and that made the task of understanding the details of Li more difficult. The object of Li was:

The technical solution proposed was an apparatus for relieving itch by heating including a power supply inside a case, including a heater at a port of the case, a temperature controlling electronic heating device which consists of a thermal probe inside the heater, a temperature selection switch, a temperature controlling circuit “and can cause the heater to generate temperatures of 52^oC – 59^oC and heat discontinuously”. The heater is a triode transistor and the thermal probe is a thermistor provided inside the triode transistor. The heater is of PTC heating material, and the thermal probe is an electric contact thermometer and provided in the PTC heating material. The specification continues:

The specification then describes the general method of operation of the invention:

The specification continues by referring to a number of figures. Two of the figures are described as a circuit diagram of one of the embodiments of the invention. The specification proceeds to describe the first embodiment of the invention. It first describes how the heater is controlled and activated, concluding this part of the description by saying:

The grammar of that sentence is obscure. It continues:

It was common ground that the circuit diagram which Li said described this embodiment did not show any means of discontinuous heating for pre-determined periods. As Mr Yee put it in his second report:

Professor Ivey agreed. He said:

But at that point the experts’ views diverged. Mr Yee said:

Professor Ivey on the other hand said:

Mr Vanhegan put a rather different case in cross-examination, which focussed on the description of the net, the connecting rod and the cam mechanism. Professor Ivey agreed that this described a mechanism by which once the triode has reached a set temperature it is extended to the net for three seconds and then contracts back for one second when the triode drops below the set temperature. However, he did not agree that this would be achieved by a timing circuit. He envisaged a circuit that measured temperature in the way that the illustrated circuit did, and then in some way operated a motor and a cam that allowed the heater to go in and out. But he did agree that whatever circuit operated the connecting rod and cam would have to be a different circuit from that illustrated in Li. So far as the period of 3 seconds on and three seconds off were concerned, Prof. Ivey thought that what Li was reporting was merely what he observed when he switched it on given the particular choice of components that he had made rather than the intended duty cycle on/off period.

Mr Yee did not refer to this passage of the specification in either of his two reports. In the course of his cross-examination he did, however, give some evidence about it. The net, he said, could be any substance that would hold heat (e.g. a piece of cloth or nylon mesh). The net was not the same as the triode, so that the net was not itself the heater or hotplate. His reading of the relevant passage in the specification was that the triode was moved forward to the net and the net itself was heated for a period of three seconds, following which the triode contracted back into the case for one second. His cross-examination continued:

He added that “the temperature of T₁ … should be relatively constant as controlled by the control circuit.” A later passage of his evidence went like this:

There are, in my judgment, two real difficulties in holding that Li anticipates the patent in suit. The first is that the reading now relied on was not one that seems to have occurred either to Mr Yee or to Professor Ivey when they prepared their reports. If it did not occur to either of these experts it is difficult to say that the skilled reader would understand that Li contains “clear and unmistakeable directions” to make something that would infringe the patent in suit. Second, the reading now relied on envisages the net being heated for 3 seconds and cooled for 1 second, with the heater being maintained at a relatively constant temperature. The length of time for which the heater remains heated is determined by the user rather than by the device itself. However, the claim in the patent in suit requires the hotplate (or heater) to be maintained at the maximum temperature for 2 to 12 seconds. Li does not disclose this feature.

I conclude, therefore that Li does not anticipate the patent in suit.

Mr Vanhegan argued that it is the dual control of maximum temperature with time that is the heart of the alleged invention. I agree that this is undoubtedly part of the invention; but in my judgment the inventive concept of the patent in suit is that both the temperature at which heat is applied and the duration of the application of heat are controlled by the device itself rather than by the user. As Mr Burkill put it, it has both a thermostat and a timer. The prior art relied on the user to control the length of time for which heat was applied. He or she would apply heat until either the itch stopped or the pain caused by the heat became too great for comfort (what Professor Friedmann called “the ouch reflex”).

The cited prior art was Li (already mentioned), a device manufactured by Dr Li called the Itch Stopper and a patent application (FR 2 746 296 A1) (“Lombal”). They all worked in much the same way as the device described in Li, that is by applying heat and relying on the “ouch reflex” to limit the duration of the application. It is not, I think, necessary to describe them further.

The short question is: would it have been obvious to add a timer to the prior art? It is not disputed that if the idea of adding a timer had occurred to the skilled reader confronted with the prior art, and he had decided to implement it, the implementation of that idea would have been simple and would have used well-known technology. So the real question is: would the idea of adding a timer and the decision to implement that idea have been obvious?

Both the medical experts agreed that, although the treatment of insect bites and stings by the application of heat was not an accepted method of treatment they would not have dismissed the prior art out of hand as being the medical equivalent of a perpetual motion machine. They would have been interested in the prior art.

The first limb of the obviousness attack was the allegation that the claimed invention was completely useless or, if not completely useless, was a backward step in relation to the prior art. For the legal underpinning of this submission Mr Vanhegan referred to a passage in Blanco White: Patents for Inventions which reads as follows:

However, this passage was written in the context of the Patents Act 1949 under which lack of utility was a ground of objection. In any event, “nonsense” sets the bar high; and neither expert went that far so far as the underlying theory of heat treatment was concerned. Moreover even if the explanation of the mechanism by which the treatment worked (i.e. the neutralisation of poisons) was wrong that would not, as Mr Burkill submitted, have prevented or deterred anyone from making or using the device claimed. But Mr Vanhegan had another way of putting this point. He said that the narrower theory underlying the claim was that a device operating within the time and temperature parameters claimed in claim 1 was stated in the specification to be a product that was both effective in treating bites and stings and also safe to use. In fact the evidence was that if the device operated at some of the temperatures claimed in the claim (e.g. 65^oC for 2 seconds) it would be very likely to burn the user. Thus it failed to achieve one of its twin objectives, viz. to be safe (or, in the language of the specification, “without, at the same time, skin irritations occurring that are attributable to the exposure to heat”).

One of the grounds on which a patent may be revoked is that the invention is not a patentable invention: Patents Act 1977 s. 72 (1) (a). Bundled up in this description are a number of different features. For example an invention may not be patentable because it is not new; or because it is not capable of industrial application or because it does not involve an inventive step. If, in Mr Blanco White’s words, an invention is “nonsensical” it would, I think, be disqualified from being a patentable invention not because it did not involve an inventive step, but because it was not capable of industrial application. That is the ground on which applications to patent perpetual motion machines are rejected. The mere fact that a claim fails to achieve its object as set out in the specification does not, in my judgment, prevent what is claimed from being patentable. Nor, in my judgment, does the law prevent someone from claiming an invention that is not safe to use. In my judgment, therefore, this ground of objection fails.

The other limb of Mr Vanhegan’s attack, based on a more conventional approach to obviousness, was diametrically opposed to the first. Far from saying that it was useless to add a timer, he said that it was obvious to do so. As mentioned the prior art relied on the “ouch reflex” to prevent users from burning themselves. If a timer were added its only utility in the majority of cases would be to override the “ouch reflex”, because if the user felt pain before the timer cut out he would simply remove the device from the skin. Dr Behrens thought that adding a timer might itself be dangerous because it might encourage users to use the device for too long. As he explained in his oral evidence:

He also explained that given the length of time that the application of heat would need to cause damage was itself uncertain, it would be difficult to predetermine the length of time that a timer would have to operate. He added:

He summarised his position in the following exchange:

In the light of that evidence it seems to me that if anyone had had the idea of adding a timer to the prior art it would not have been obvious to put the idea into practice. There would have been no motive to do so. In so far as the prior art worked at all, it worked without a timer, relying solely on the “ouch reflex” to prevent damage to the users of the devices; and the introduction of a timer might have had serious deleterious effects. Whether it did or not would depend on the temperatures and the durations for which the timer was set. These dual parameters were not part of common general knowledge and the prior art gave little guidance. Mr Vanhegan put to Professor Friedmann some classes of user who might be assisted by a timer (the stoical, the masochistic and the elderly) and to some extent Professor Friedmann accepted that for these classes of user a timer might be a good idea. But that, to my mind, came nowhere near establishing that it was obvious to add a timer to the device. As Mr Burkill put it, there would have been pros and cons in adding a timer.

In my judgment therefore the obviousness attack fails.

The action began in response to a letter sent by Riemser’s German patent attorneys (who were not acting on behalf of the First Defendant BSM-Bionic). It was sent to a large number of Boots stores who were stocking the Zeno device; and to other retailers in Europe. The letter set out the patent in suit and continued:

Section 70 of the Patents Act 1977 as amended provides (so far as relevant):

It is common ground that Tyrell qualifies as a “person aggrieved”. It is also common ground that whether a threat has been made depends on how the communication would be understood by an ordinary reader in the position of the recipient of the communication. It is also common ground that a threat may be explicit or implicit. In L’Oreal (UK) Ltd v Johnson & Johnson[2000] FSR 686 Lightman J said that a threat may be “veiled or covert, conditional or future”. These propositions are established by authorities that pre-date the amendment to section 70. Sub-section (5) was one of the provisions introduced by the amendment. The reasonable reader must now, I think, be taken to be aware that communications will not amount to threats if they do no more than is permitted by that sub-section. On the other hand, the very fact that subsection (5) is an exception carved out of section 70 (1) leads to the conclusion that, if a communication does not fall within that subsection, the meaning of “[threatening] proceedings” must be a wide one. On the basis of my construction of the patent in suit, Riemser has not proved infringement, so that subsection (2A) does not apply.

In the present case:

The letter did not mention proceedings or explicitly threaten them;

The letter asserted that “up to this point” the writer could see no difference in the technical solution; but contained a request for the reason why the recipient thought that it need not “take into consideration” the patent;

The writer of the letter was not an English lawyer to whom the conduct of proceedings about patent infringement in England would usually be entrusted.

On the other hand, the letter was not addressed to the manufacturer of Zeno, nor even to Boots head office. It was sent to the stores that were actually stocking the product.

The packaging in which the Zeno product was sold displayed the name and address of the manufacturer in Houston Texas and its UK distributor.

The writer of the letter knew who had manufactured the Zeno device; who had imported it and who was offering it for sale. So the purpose of the letter cannot have been to discover who was infringing the patent (if indeed it was being infringed).

Was the “sole purpose” of the letter to discover whether the patent had been infringed? If the writer of the letter were genuinely concerned to ask about some technical characteristic of the Zeno device that would point out a difference between that device and the device described in the patent the obvious person to write to would be the manufacturer. Why should the retailer know the technical details of what it sold? And even if the retailer did know, surely the relevant person would be someone in head office responsible for Boots’ corporate decision to stock it rather than any individual store manager. Why, then, were the letters sent to the retailers? The only answer must be to persuade them to stop selling the Zeno device. It partially succeeded in that objective. In my judgment that means that it cannot be said that “the sole purpose” of the letter was to discover whether the patent had been infringed.

It is true that the letter made assertions about the patent; but it also made assertions about the Zeno device.

Mr Burkill objected that no evidence had been called from Boots to show how they interpreted the letter. I do not think that matters. In Mannai Investment Co Ltd v Eagle Star Life Assurance Co Ltd[1997] A.C. 749 the question was whether a notice given by a tenant to a landlord was valid to terminate a lease. Lord Steyn said:

In my judgment the same applies here. It is not a question of how Boots understood the letter; but how a reasonable person in the position of Boots would have understood it. Read in context, through the eyes of a retailer, the letter amounted, in my judgment, to a veiled threat of infringement proceedings.

The patent in suit is valid but not infringed.

Riemser (but not BSM-Bionic) is liable for unjustified threats.

I will hear discussion on the form of relief to be granted. In principle I am prepared to grant a declaration of non-infringement; a certificate of contested validity; and an order for an inquiry into damages.