Halliburton Energy Services Inc v Smith International (North Sea) Ltd & Ors

This is the judgment of the Court on an application made in a pending appeal from an order made on 27 July 2005 by Mr Justice Pumfrey in patent proceedings brought by Halliburton Energy Services Inc (“Halliburton”) against Smith International (North Sea) Limited and others. The circumstances in which that appeal comes before the Court, notwithstanding that, since the order of 27 July 2005, the underlying dispute between those parties has been settled by agreement, are explained in the judgment delivered by Lord Justice Jacob, sitting with Lord Justice Rix, on 21 February 2006 ([2006] EWCA Civ 185) on an earlier application.

The outcome of that earlier application was that, notwithstanding the settlement of the underlying dispute, the appeal from the order declaring the patents in suit to be invalid is to be heard on its merits. The Court, with the encouragement of Halliburton, directed that a scientific adviser be appointed to assist. Halliburton were to attempt to identify a suitable candidate, whose appointment would be subject to the approval of the Court: paragraph 2 of the order made on 21 February 2006.

On 16 August 2006 Halliburton’s solicitors informed the Court that they had identified Professor David Limebeer, Head of the Department of Electrical and Electronic Engineering and Professor of Control Engineering at Imperial College, London, as a suitable candidate for appointment. The Treasury Solicitor, on behalf of the Comptroller General of Patents (who had accepted the invitation of the Court to exercise the right to appear on the appeal conferred by paragraph 21.2(6) of the Practice Direction supplemental to CPR Pt.52 [52PD.100]), indicated that there was no objection to the appointment of Professor Limebeer as scientific adviser. He was appointed by Lord Justice Jacob, on behalf of the Court, on 23 September 2006.

In or about the third week of October 2006 Halliburton’s solicitors sent to Professor Limebeer the document bundles which they had prepared for use at the hearing of the appeal, fixed to commence on 22 November 2006. They did so in compliance with directions given by Lord Justice Jacob. The purpose of those directions was to enable the Professor to become familiar with the scientific issues which would be likely to arise on the appeal. Professor Limebeer began the process of studying those documents. On 29 October 2006, on his own initiative, he sent an e-mail message to the three members of the Court. His purpose – as he explained in the first paragraph of that message – was “to highlight what I believe are the key engineering issues in dispute and to propose a possible way forward”. A copy of that e-mail message – to which, for convenience, we will refer as “Professor Limebeer’s Note” or “the Note” – is annexed to this judgment as an Appendix.

The Court sent copies of Professor Limebeer’s Note to counsel instructed, respectively, on behalf of Halliburton and the Comptroller. Halliburton’s response, in a note from counsel received on or about 9 November 2006, was to invite the Court to revoke the Professor’s appointment as scientific adviser. Counsel wrote:

“Regretfully it is Halliburton’s position that Professor Limebeer has misunderstood his role in this case and has thereby disqualified himself as acting as scientific advisor to the Court.”

And, after some discussion of the role of a scientific adviser, counsel went on to say this:

“Professor Limebeer has expressed opinions which are for this Court to decide and are not within the remit of the advisor. In short Halliburton submit that Professor Limebeer cannot continue to act as the advisor. The statements in his note (which the lay clients have seen) would mean that they could have no confidence in Professor Limebeer’s impartiality or ability to avoid becoming an advocate in the case.”

It was submitted that the only practical way forward was for the appeal to be adjourned to allow the appointment of an adviser in the place of Professor Limebeer. It was accepted that it would not be sensible for the Court to proceed to hear the appeal without the assistance of a scientific adviser; and it was recognised, realistically, that a substitute appointment could not be made within the time available before 22 November 2006.

It was in those circumstances that the appeal was listed for directions on 16 November 2006. Although, formally, the application then before the Court was for an adjournment of the appeal hearing, in substance the question for decision was whether the appointment of Professor Limebeer as scientific adviser should be revoked. It was not in dispute that, if the appointment were revoked, an adjournment would be inevitable; but it was not suggested that, if the appointment were not revoked, the appeal could not proceed as listed. The Comptroller took the view that it was not necessary, in the interests of justice, to revoke the appointment.

After taking time to consider the submissions advanced before us at the oral hearing on 16 November 2006, we reached the conclusion that it was not necessary to revoke the appointment. We notified that decision to counsel, so that they could continue preparation for the appeal hearing. This judgment sets out our reasons for that decision.

The power to appoint a scientific adviser to assist the Court of Appeal in a patent appeal is conferred by section 54(9), read with section 70(3), of the Supreme Court Act 1981. Provision is made by CPR 35.15 “where the court appoints one or more persons (an “assessor”) under section 70 of [the 1981 Act]”. The rule is in these terms, so far as material:

“35.15

(2) The assessor shall assist the court in dealing with a matter in which the assessor has skill and experience.

(3)

The assessor shall take such part in the proceedings as the court may direct and in particular the court may -

(a)

direct the assessor to prepare a report for the court on any matter at issue in the proceedings; and

(b)

direct the assessor to attend the whole or any part of the trial to advise the court on any such matter.

(4)

If the assessor prepares a report for the court before the trial has begun –

(a)

the court will send a copy to each of the parties; and

(b)

the parties may use it at trial.

. . . ”

Although section 70 of the Act makes a distinction between “assessors” (sub-sections (1) and (2)) and “scientific advisers” (sub-sections (3) and (4)) CPR 35.15 does not do so. It is clear that, when the rule refers to “assessor”, it includes a scientific adviser appointed under sections 54(9) and 70(3) of the 1981 Act.

There is no doubt that the position, now, is governed by CPR 35.15. Subject to the matter being one in which the adviser has skill and experience, the Court may direct that the adviser take such part in the proceedings and give advice on such matters in issue as it thinks will be of assistance. Nevertheless, we were taken through the historical antecedents which show how the use of assessors has developed in patent matters. We are indebted to the Comptroller, members of the Patent Office and counsel, Mr Tappin, for their research.

The power of the court (including the Court of Appeal) to “call in the aid of an assessor specially qualified, and try and hear the case wholly or partially with his assistance” can be found in the Patents Act 1883 (section 28(1) and (2)) and in the 1907 Act (section 31(1) and (2)). It appears that little use was made of that power. The second interim report (1946) of the Departmental Committee charged with considering reform of the Patents and Designs Acts (the Swan Committee) contained the following observations, at paragraphs 122 to 125 (Scientific advisers in patent actions):

“122.

Under Section 31 of the Acts, the Court may, if it thinks fit, and shall, on the request of all the parties, call in an assessor, and shall try the case wholly or partly with his assistance . . .

123.

Little use has been made of these provisions, and experience has shown that patent litigants are not as a rule favourably disposed towards having their cases tried with the help of an assessor or assessors. . . . . [The] chief objection to the employment of assessors appears to be that important issues in the action may be prejudicially affected or indeed decided by the opinion of a man whose views counsel have no means of ascertaining, and with whom there is, in consequence, no opportunity or basis for discussion or argument. . . . We are, however of the opinion that useful service could be rendered by the presence of a specially qualified person to assist the Court upon the purely technical aspects of a case, even in proceedings where the Judge also possesses scientific qualifications; for no Judge, however well-equipped, could possibly keep in touch with the manifold and rapid advances occurring in every branch of scientific knowledge. Consequently, with the increasing complexity of industrial processes, it will become increasingly necessary for specialised assistance to be available to any Court engaged in the trial of patent actions.

124.

We accordingly recommend that a scientific assistant should sit on all occasions with the special Judge or Judges appointed to try patent actions, unless . . . the Judge . . . decides that such assistance is unnecessary. . . . We do not, however, consider it necessary or indeed desirable that a person of scientific eminence should be selected to fulfil the role of scientific assistant to the Court; neither do we favour the continued use of the term ‘assessor’ to describe the type of assistant we have in mind. His function should not be to assist in the trial of matters in issue, but to elucidate the technical aspects of the case. The essential qualification of the proposed scientific assistant should be an expert knowledge of the art involved. . . .

125.

We also wish to record the view that patent proceedings would be considerably shortened, with saving of expense to the parties, if Judges made it their practice . . . so to arrange their lists . . . as to enable them to peruse and study the technical aspects of the a case with the help of a scientific assistant before the hearing of an action . . .”.

The Swan Committee report was followed by the Patents Act 1949. There was no provision in the 1949 Act in terms equivalent to those in the earlier Acts. But section 84(2) of that Act provided that rules of court should “make provision for the appointment of scientific advisers to assist the court in proceedings for the infringement of patents . . . and for regulating the functions of such advisers”. Order 37A was introduced into the Rules of the Supreme Court for that purpose: rule 12 enabled the court to appoint “an independent scientific adviser to assist the Court or to enquire into and report on any question of fact or of opinion not involving questions of law or construction”. That rule was replaced (but in substantially the same terms) by Order 103, rule 27 of the Rules of the Supreme Court 1965.

An appointment was made by this Court under Order 103 rule 27, RSC 1965 in Valensi and another v British Radio Corporation Limited [1971] FSR 403. That was, it seems, the first appointment of an assessor or special adviser to be made since 1936. It is pertinent to note the observations of Lord Denning, Master of the Rolls:

“This is an application concerning the validity of a patent in relation to colour television. We have looked at the specification and other matters. It is a case of extreme complication. We are satisfied that it is a proper case in which the court should appoint a scientific adviser to assist the court. We should appoint the man best qualified to assist. On the information before us, such a man is Mr Gouriet, who is the Chief Engineer of the Research Department of the British Broadcasting Corporation. We therefore appoint him as independent scientific adviser to assist the court . . .”.

It can be seen that the suggestion that it was neither necessary nor desirable that a person of scientific eminence should be selected - made at paragraph 124 in the Swan Committee report – had not taken root. Notwithstanding the submission of counsel of the plaintiffs in Valensi that “it was quite unnecessary for a person of Mr Gouriet’s standard to sit in the court just in case the court required help”, the Court appointed him as “the man best qualified to assist”. In its judgment on the hearing of the substantive appeal [1973] RPC 337, 350, the Court (Lord Justice Russell, Lord Justice Buckley and Lord Justice Cairns) referred to the technical problems as “exceedingly difficult to grasp” and commented on the “great advantage” which they had derived from Mr Gouriet’s assistance.

Section 84(2) of the 1949 Act was replaced, in substantially the same terms, by section 96(4) of the Patents Act 1977. That section was, in turn, replaced – again in substantially the same terms - by section 70(3) of the Supreme Court Act 1981, to which we have already referred. In 1986 Order 103, rule 27, RSC 1965 was replaced by Order 104, rule 15:

“15 (1) In any proceedings under the 1949 or 1977 Act, the Court may at any time, and on or without the application of any party, appoint an independent scientific adviser to assist the Court, either –

(a)

by sitting with the judge at the trial or hearing of the proceedings, or

(b)

by inquiring and reporting on any question of fact or of opinion not involving a question of law or construction,

according as the Court may direct.

(2)

The Court may nominate the scientific adviser and, where appropriate, settle any question or instructions to be submitted or given to him.”

An appointment was made by this Court under Order 104, rule 15 RSC 1965 in In re Genentech’s Patent, Genentech Inc and another v The Wellcome Foundation Limited [1989] RPC 147. The appointee, Dr Brenner, was a scientist of international reputation and, subsequently, a Nobel Laureate. At the outset of the hearing (transcript, 27 June 1988) Lord Justice Purchas (speaking on behalf of the Court) said this:

“The time we have spent, each of us, in preparation may be measured in days rather than in hours and although pre-reading has not included all the documents indicated, with the assistance of Dr Brenner we hope that we have achieved a superficial acquaintanceship, if not a full understanding of the elementary aspects of recombinant DNA technology and its particular relationship to the synthesis of tissue plasminogen activate. . . .

I would like to say how grateful we are that we have been given the assistance of Dr Brenner . . . [He] will for the next three weeks be sitting with us as a scientific adviser and will be available to us out of court for consultation and instruction on purely scientific matters. He will not take part in any way in the decision making process. If by chance we become conscious that the advice he gives us may touch upon controversial matters such as the historical development of the art and that this might affect our judgments we will give each of you warning about this and an opportunity to address us before we prepare our judgments. . . .”

Lord Justice Purchas referred to those remarks in the final paragraph of his judgment on the appeal (ibid, 235, lines 16-21):

“Finally, I would add, in view of what I said at Day 1, page 2H of the transcripts concerning the role to be played by Dr Brenner, that Dr Brenner has played no part in the judicial decision-making process, nor has his advice had any influence upon that process, other than to provide a scientific factual background. Having said that, I would wish to repeat my acknowledgment of the inestimable assistance he has given to the court.”

Lord Justice Dillon added his own tribute (ibid, 235, lines 26-28):

“I would also wish at the very outset of this judgment to express my thanks to Dr Brenner, for his explanations of the scientific terms and procedures involved. Without those explanations, I would not, I apprehend, have come even remotely near to achieving some glimmering of what the scientific issues in this case are about.”

Dr Brenner was, again, scientific adviser to the Court in Chiron Corporation and others v Murex Diagnostics Ltd and others, Chiron Corporation and others v Organon Teknika Ltd and others [1996] RPC 535 - as he had been at first instance in that case. Lord Justice Morritt, delivering the judgment of the Court, said this (ibid, 634, lines 30-38):

“Finally, no acknowledgments of ours would be complete without an expression of our debt to our scientific adviser, Dr Sydney Brenner. That a scientist as eminent and busy as he, was prepared to give up all the time necessary both during and after the hearing in order to instruct the court in molecular biology was remarkable in itself. But together with great learning he brought to his task total neutrality, a scrupulous capacity to avoid any expression of opinion on legal matters, unfaltering good humour, and a rare ability to communicate. In short, without him in this unfamiliar field our understanding of the facts would have been insufficient.”

Other cases in which scientific advisers were appointed by this Court under Order 104 rule 15 include Willemijn Houdstermaatschappij BV v Madge Networks Ltd [1992] RPC 386 and Biogen Inc v Medeva Plc [1995] RPC 25. In the former, Lord Justice Stuart-Smith observed (ibid, 388, lines 29-31) that, in his role as scientific adviser, Professor Halsall of the University of Essex had “explained to the court technical aspects of the evidence. He has not attempted to go outside the evidence in the case, nor has he been asked to construe the patent”. In the latter, Lord Justice Hobhouse referred (ibid, 68, lines 25-17) to the “patient assistance which they have given us in understanding the technical scientific matters raised before us”. In Biogen the same advisers gave assistance to the House of Lords, [1997] RPC 1. Lord Goff of Chieveley (ibid, 31, lines 17-20) expressed the gratitude of the Appellate Committee for their “invaluable assistance both before and during the hearing”.

For completeness we should mention the form in which the House of Lords received assistance from Professor Yudkin in Kirin-Amgen Inc v Hoechst Marion Rousel Ltd [2005] RPC 169. The position is described by Lord Hope of Craighead (ibid, 20, [135]):

“Before leaving the case, however, I would like to pay a particularly warm tribute to the valuable assistance which, with the agreement of the parties and in common with others of your Lordships, I received from Professor Michael D. Yudkin, Professor of Biochemistry at Oxford University, in a series of seminars which he gave in camera before the appeal was heard to introduce us to the relevant aspects of the recombinant DNA technology. The work which Professor Yudkin did by means of these carefully prepared seminars enabled all those involved to concentrate on the issues of law in the appeal without having to spend a good deal of extra time in the course of the hearing on learning about the technology. This had the effect of shortening the length of time that it was necessary to devote to the hearing by several days. It was at Lord Hoffmann’s suggestion in the course of a preliminary hearing that this was done, as there was no dispute about the technology. I suggest that it is a course which might usefully be adopted in the future in cases of this kind, where the technology is complex and undisputed and the parties are willing to consent to it.”

It is important to have in mind that section 70 of the Supreme Court Act 1981 – which, at sub-section (3), provides for the appointment of scientific advisers – provides also, at sub-section (1), for the appointment of assessors in the sense traditionally understood in maritime cases. As we have said, CPR 35.15 applies to appointments under each of those sub-sections. It is helpful, therefore, to note the observations of Lord Justice Clarke in a postscript to the judgment of the Court (Lord Phillips of Worth Matravers, Master of the Rolls, Lord Justice Clarke and Lord Justice Sedley) in The owners of the ship “Bow Spring” v The owners of the ship “Manzanillo II” [2004] EWCA Civ 1007, [57] – [65], [2005] 1 Lloyd’s Rep 1, on the need for fairness. He said this (so far as material)

“[57] The common law principles of natural justice anticipated by many years the concept of a fair trial which has been elaborated by the European Court of Human Rights under Article 6(1) of the Convention. This Article provides, among other things, that in the determination of his civil rights and obligations everyone is entitled to a fair and public hearing before an independent and impartial tribunal established by law.

[58] Both the common law and the Convention regard fairness as including the need for the court to know, before it reaches a conclusion, what the parties have to say about the issues and the evidence which goes to them. As the Strasbourg court put it in Kr Ma v Czech Republic (35376/97; 3 March 2000, para 40):

‘The concept of a fair hearing … implies the right to adversarial proceedings, according to which the parties must have the opportunity not only to make known any evidence needed for their claims to succeed, but also to have knowledge of, and comment on, all evidence adduced or observations filed with a view to influencing the court's decision.’

[59] Where the court has evidence from an expert who has not been called as a witness by either party - and CPR 61.12 makes it clear that nautical assessors are such experts - the principle needs to be adapted to the procedure. Its effect is that any consultation between the assessors and the court should take place openly as part of the assembling of evidence. Because the judge is not bound to accept the advice he receives from the assessors (see The Ansonia (1920) 2 Ll L Rep 123, 124), the parties are entitled to an opportunity to contend that he should or should not follow it. In many, perhaps most, cases the questions and advice taken together will be susceptible of little or no argument that has not already been directed to the issues which have prompted the questions. But fairness requires the opportunity to be given.”

And, after explaining the earlier practice noted in The Hannibal (1867) LR 2 Ad&E 53, 56, he went on

“[61] Such a practice would not, in our view, be compatible with Article 6; and it is right that, except in cases where such a discussion is unnecessary in the light of submissions made earlier, the preferable modern practice of putting questions to the assessors after discussion with counsel should be complemented by a practice of disclosing their answers to counsel, either orally or in writing - in order that any appropriate submission can be made as to whether the judge should accept their advice. ”

We understand that to be the practice now adopted in the Admiralty Court – see the guidance given by Mr Justice Gross in The owners of the ship “Global Mariner” v The owners of the ship “Atlantic Crusader” [2005] EWHC 380 (Admlty), [14], [2005] 1 Lloyd’s Rep 699. But, as Mr Justice Gross observed (ibid, [16]):

“[16] The aim is to strike the right (and proportionate) balance between the desirable goal of transparency on the one hand and the need to curb the cost and delay inherent in the ‘ping pong’ of post-hearing exchanges on the other.”

We find guidance, also, in the judgment of the Supreme Court of Canada in Porto Segura Companhia De Seguros v Belcan SA and others (the vessel “Federal Danube”) [1997] 3 S.C.R 1278. The Supreme Court was considering whether the rule in admiralty cases - that, when a judge sits with assessors, expert evidence is not called by the parties – should be revised. Justice McLachlin, delivering the judgment of the Court, explained that the rule suffered from four defects; of which it is sufficient, in the present context, to mention only the third:

“[35] . . . the fact that [the present rule] does not permit disclosure to the parties of what passes between the judge and the assessor. Such disclosure may not be required where the assessor functions only to assist the judge in understanding technical evidence, particularly if expert evidence has been introduced on the issue in question. Where assessors venture opinions on factual matters at issue between the parties, however, natural justice requires more.”

. . .

At paragraph [40] she said this:

“[40] I conclude that the old admiralty rule appointing assessors to assist the judge in making findings of fault to the exclusion of expert evidence should be revised. First, assessors should be permitted to assist judges in understanding technical evidence. Second, assessors may go further and advise the judge on matters of fact in dispute between the parties, but only on condition of disclosure and a right of response sufficient to comply with the requirements of natural justice. In all cases, the parties are entitled to call expert evidence subject to the limits and procedures set out in the Evidence Act and the rules of practice. I state these propositions as general guidelines, aware that it may be necessary or useful for the judge in a particular case, upon consultation with the parties, to vary how assessors are used and what procedures should be followed, depending on the nature of the trial and the issues to be determined. The essential is that the principles of natural justice that protect a fair trial should in all cases be preserved.”

We are not, of course, concerned in the present case with the admiralty rule which prevents parties from calling expert evidence. In patent cases the parties are entitled to call expert evidence; and they usually do so. They did so at the trial in the present proceedings; and the judge made findings of fact based on that evidence. But we note that the Supreme Court of Canada recognised that the assistance which assessors could give to the court was not limited to “understanding technical evidence”. Assistance might also be needed on “matters of fact that were in dispute between the parties”. Assistance on such matters could properly be sought and given; but subject always to the overriding requirement of fairness. That requirement would be met by disclosure and “a right of response sufficient to comply with the requirements of natural justice”. That, as it seems to us, is consistent with the approach commended by this Court in the Manzanillo II.

In our view the approach of the Supreme Court of Canada in the Federal Danube and of this Court in the Manzanillo II – adapted to meet the particular needs of an appellate court in a patent case (where the trial judge has already made findings of fact) – is one which we should follow. We should not deny ourselves the assistance which the special adviser can give in helping us to understand the expert evidence given at the trial; in helping us to consider whether there are grounds to think (from the manner in which he has dealt with that evidence in his judgment) that the judge has failed fully to understand that evidence; and in helping us to evaluate the factual conclusions which the judge has reached on the basis of that evidence. But we must keep in mind the overriding requirement of fairness. And we must keep in mind that it is our task – and not that of the special adviser – to decide the appeal.

It is important to appreciate that, as appears from the first paragraph of his Note, Professor Limebeer has understood and accepted that it is not for him to offer an opinion on legal matters. He observed:

“I am aware of the fact that legal matters are not for me, and that I should be cautious about introducing opinions of my own. If I have strayed across any of these boundaries I apologise in advance: some of the borders are poorly defined and therefore easily transgressed.”

In the present case there is much force in the observation that the borders between the science and the law are blurred.

It is important, also, to appreciate that the Note is, as Professor Limebeer points out in the first paragraph, intended as “a first progress report”; and that, as he notes in the penultimate paragraph, “some of my thinking is probably still poorly defined”. It is clear that the Note was written in order to assist the Court in identifying the scientific issues that would have to be addressed on the appeal. Indeed, the Professor – without, perhaps, a lawyer’s understanding of the limitations inherent in the appeal process – has taken the view that a sensible way forward would be to probe the engineering issues with Halliburton’s advisers, and with the Comptroller, at a pre-trial meeting. We reject the criticism that the Note leads to the conclusion (or even to the suspicion) that Professor Limebeer will approach his task of informing and advising the Court over the course of the appeal with a closed mind.

Counsel for Halliburton expressed concern as to the very proper disclosure by Professor Limebeer, in the fourth paragraph of the Note, that “I know David Newland personally as well as through his scientific work.” Professor Newland – who held the 1875 Chair in Engineering at Cambridge University from 1976 to 2003 and is now Emeritus Professor of Engineering at that university – gave evidence at the trial, much of which was accepted by the judge. We had already taken steps to satisfy ourselves that Professor Limebeer’s acquaintance with Professor Newland was nothing more than that which would be expected between two distinguished academics working in the same field; and we were able to share his response with counsel at the hearing of this application. For completeness we set out Professor Limebeer’s comment on this point:

“David Newland is a well known Cambridge Professor (as well as a past Head of Department) who works in mechanical dynamics and so is likely to be known by the whole UK multibody mechanical modelling community. In that respect there is nothing special about my relationship with Newland.”

It seems to us inevitable that experts in the same discipline will have met in the course of their work. We do not regard that as a matter which should give rise to any concern as to partiality.

Counsel expressed concern, also, at Professor Limebeer’s observation – which appears in two passages of the Note – that Halliburton’s criticism of Professor Newland (at paragraph E in the skeleton argument and at paragraph C in appendix I to the skeleton) shows a tendency “to play the man rather than the ball”. We are satisfied that that concern is without foundation. As we understand the issues on this appeal (at what is, necessarily, a very early stage in the development of those issues) it is important to Halliburton’s case that we be persuaded that Professor Newland did not have relevant expertise in relation to the design of rock drill bits; and that that lack of relevant expertise infected (and should have led the judge to discount) his evidence in relation to computer modelling in that context. Whether that case can be made out is, of course, a matter for the Court to decide after hearing argument on the appeal. But the fact that that is the case advanced (if our understanding is correct) leads to Professor Newland becoming identified as both the man and the ball. In that sense it is impossible for Halliburton to play what (on this analysis) it must see as the ball (Professor Newland’s lack of relevant expertise) without also playing the man. We do not see the passages in Professor Limebeer’s Note as doing more than point that out.

We recognise that there are passages in the Note where Professor Limebeer expresses his own opinion on matters which were for the judge; and on which the judge has made his findings. One example is the make-up of the “skilled team” (paragraphs D, G and H in Halliburton’s skeleton, paragraph A in the Comptroller’s skeleton). Whether the judge was entitled to make the findings that he did on the evidence which was before him is, of course, a matter for the Court. Professor Limebeer’s role – as we have sought to explain – is to help us understand that evidence, to help us consider whether the judge fully understood that evidence, and to help us evaluate the conclusions which the judge reached on that evidence. It is, we think, inevitable that there will be matters in a field as complex as computer modelling upon which it will be impossible for a scientific adviser as skilled and experienced as Professor Limebeer to avoid expressing an opinion. The requirement of fairness is met by disclosing that opinion and providing the parties with the opportunity to comment upon it. Disclosure of the opinions expressed in the Note has been made. The parties will have the opportunity to comment as they think fit. But it is important to keep in mind that the scientific adviser is not a witness. The evidence on which the Court will decide this appeal is the evidence that was before the judge.

We have given careful consideration, with the assistance of counsel (including counsel for the Comptroller) to the contents of the Note. We are satisfied that there is nothing in the Note which should lead us to the view that Professor Limebeer will not be able to give us the assistance which we will undoubtedly need in this case. Indeed, we are confident that he will be able to give us that assistance. We are confident, also, that there is nothing in the Note that should lead us to think that the overriding requirement of fairness can not be met. In that context, we observe that the Note has had a beneficial effect: in that it has led us to examine the proper role of a scientific adviser in greater depth and at an earlier stage than might otherwise have been the case.

It is said on behalf of Halliburton that it is not enough for us to be satisfied that the appeal can properly proceed. Lawyers and judges are trained to recognise the relevant and the irrelevant and to distinguish the one from the other. It is easy for us to say that we will put out of our minds opinions expressed in the Note if they are not based upon evidence before the judge. But the perception of those who are not lawyers will (or may) be different. We must have regard to perception as well as to objective reality.

In that context we were referred to the judgment of this Court (Lord Bingham of Cornhill, Chief Justice, Lord Woolf, Master of the Rolls and Sir Richard Scott, Vice-Chancellor) in the conjoined appeals in Locabail (UK) Ltd v Bayfield Properties Ltd and other matters [2000] QB 451. The judgment sets out the approach which a court should take to allegations of perceived or apparent bias: would the circumstances lead a fair-minded and informed observer to conclude that there was a real possibility (or a real danger) that the tribunal was biased. At paragraph [25] (ibid, 480G), after giving examples of circumstances which would, or would not, be likely lead to a conclusion that there was a real danger of bias, the Court said this:

“The mere fact that a judge, earlier in the same case or in a previous case, had commented adversely on a party or witness, or found the evidence of a party or witness to be unreliable, would not without more found a sustainable objection. In most cases, we think, the answer, one way or the other, will be obvious. But if in any case there is real ground for doubt, the doubt should be resolved in favour of recusal. We repeat: every application must be decided on the facts and circumstances of the individual case. . . . ”

We should emphasise two matters. First, Halliburton do not invite the members of this Court to recuse themselves. It is not suggested that, having become aware of the contents of Professor Limebeer’s Note, the members of the Court are unable (or will be perceived to be unable) to give a fair hearing to this appeal. Second, it is not suggested that the views expressed by Professor Limebeer in the Note are other than his own. There is no attack whatsoever on his integrity; nor, we may say, on his relevant expertise. It is to be kept in mind that he was appointed on the recommendation of Halliburton’s solicitors. But it is said that, if he continues to assist the Court, there will be a perception that the appeal will not receive a fair hearing.

We reject that submission. It is important to keep in mind that the relevant perception is that of the fair-minded and informed observer. The fair-minded and informed observer may be taken to have a proper understanding of the role of a scientific adviser and how that role interacts with the role of the Court. The position which the Comptroller has taken on the present application is illustrative of this approach. The Comptroller – as his counsel accepted – was, at first, minded to support Halliburton’s application. But after further thought, the Comptroller took a different view. The explanation for that change of view is set out in the Comptroller’s skeleton argument, at paragraphs 25 and 26:

“25.

. . . There is no doubt that in his email Prof. Limebeer has expressed opinions which go beyond mere elucidation of the technology and stray into matters which it is for the Court to decide. He also states that he knows Prof. Newland . . . and clearly has views as to his abilities.

26.

But the Comptroller is no longer convinced that this necessarily disqualifies Prof. Limebeer from acting as scientific adviser to the Court. After all, the Court has to decide whether to allow the appeal on the basis of the facts found by the trial judge and (to the extent that it is permissible to revisit it) the evidence given at the trial. The Court is surely well able to exercise its judicial function and to exclude from consideration any extraneous evidence or opinions. Prof. Limebeer is, after all, not the decision maker. Further, rule 35.15 allows the Court to use the scientific adviser as it wishes subject to fairness to the parties, which here includes giving Halliburton the opportunity to comment on the substance of Prof. Limebeer’s email.”

The Court can expect from the fair-minded observer an understanding of the respective roles of a scientific adviser and the Court, informed by this judgment; and can expect that understanding to lead to the conclusion which the Comptroller has reached.

It is for those reasons that we reached the conclusion, on 16 November 2006, that it was unnecessary to revoke the appointment of Professor Limebeer as scientific advisor; and so unnecessary to adjourn the hearing of the appeal.