I. Introduction

Your client just got sued for patent infringement, or just filed suit for patent infringement. Early in the case, you and your client will need to carefully consider whether or not a patent law expert needs to be retained, and if so, which one should be retained. Once retained, you need to optimize your working relationship with your patent law expert. Although the role of patent law experts in patent litigation has diminished to some degree over the years, they are still widely employed and can play a pivotal role in winning your case. Understanding the current role of patent law experts in patent litigation will help you decide whether or not to retain such an expert on behalf of your client. In order to make this critical decision, you need to know and understand: 1) the historical use of patent law experts; 2) the current law governing the permissible scope of their testimony; 3) the areas in which they may testify; 4) considerations in selecting an appropriate patent law expert; 5) the mechanics of working with such an expert; and 6) what your expert might face from opposing counsel during depositions and at trial.

II. Historical Use of Patent Law Experts

The first patent trials in the United States were as troubling to federal judges as they are today. In the 1800's, patents and admiralty were two areas of the law that were considered so arcane that expert testimony from lawyers was frequently permitted, usually to enable the judge to understand the legal principles involved. Prior to the enactment of the modern U.S. patent law in 1952, patent lawyers were sometimes allowed to give opinion testimony at trial on the ultimate issues of patent validity and infringement. However, federal judges eventually grew tired of hearing dueling patent law "experts" and began imposing limitations on their testimony at trial. Justice Learned Hand stated many years ago:

"We have not the slightest wish to minimize the vital importance of expert testimony in patent suits, or suggest that we are not absolutely dependent upon it within its proper scope; but that scope is often altogether misapprehended, as the appellant has misapprehended it here. Specifications are written to those skilled in the art, among whom judges are not. It therefore becomes necessary, when the terminology of the art is not comprehensible to a lay person, that so much of it as is used in the specifications should be translated into colloquial language, in short, that the judge should understand what the specifications say. This is the only permissible use of expert testimony that we recognize. When the judge has understood the specifications, he cannot avoid the responsibility of deciding himself all questions of infringement and anticipation, and the testimony of experts upon these issues is inevitably a burdensome impertinence." (emphasis added). Kohn v. Eimer et al., 265 F. 900, 902 (2nd Cir. 1920).

Prior to the advent of the United States Court of Appeals for the Federal Circuit (CAFC) in 1982, and apart from infrequent U.S. Supreme Court decisions, there was no uniform body of case law governing the substantive issues raised in patent infringement lawsuits. Before then, both patent law precedent and the outcome of patent law suits varied widely among the different circuits, often making forum selection critical to the outcome of the case. It was because of the confusion and misunderstanding surrounding the complexities of patent law that federal judges gave wide latitude to the testimony of patent law experts.

After the creation of the CAFC in 1982, that court quickly developed a uniform body of patent law case precedent, and in so doing, it began to restrict the testimony of patent law experts. Eventually, in Markman the CAFC held that claim interpretation is an issue of law for the court to decide. Markman v. Westview Instruments, Inc., 52 F.3d 967, 34 USPQ2d 1321 (Fed. Cir. 1995) (en banc), affirmed 116 S.Ct. 1384, 38 USPQ2d 1461 (1996). The CAFC has made clear its disdain for testimony by patent law experts concerning claim interpretation, stating that it "should be treated with the utmost caution, for it is no better than opinion testimony on the meaning of statutory terms." Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 39 USPQ2d 1573, 1579 (Fed. Cir. 1996). However, by way of contrast, the CAFC has held that expert technical testimony, as opposed to testimony by patent lawyers, about how those skilled in the art would interpret certain language in a patent claim may be considered "when appropriate as an inherent part of the process of claim construction and as an aid in arriving at the proper construction of the claim." Tanabe Seiyaku Co. v. United States ITC, 109 F.3d 726, 732, 41 USPQ2d 1976, (Fed. Cir. 1997).

III. Current Law Governing the Permissible Scope of Testimony of a Patent Law Expert Witness

Aside from claim construction, the CAFC has not laid down a hard and fast set of rules prescribing when patent law experts should and should not be allowed to testify. The permissible scope of trial testimony by a patent law expert is a matter of discretion with the trial judge, which discretion, of course, is limited. In Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) the U.S. Supreme Court dealt with the admissibility of scientific expert testimony and held that the Federal Rules of Evidence (FRE) "assign to the trial judge the task of ensuring that [such] an expert's testimony both rests on a reliable foundation and is relevant to the task at hand." Id., at 597. In 1999 the U.S. Supreme Court ruled that the so-called gate keeping function established in its earlier Daubert decision applies to all expert testimony, and that evidentiary rulings in this regard are reviewed under the abuse of discretion standard. Kumho Tire Co., Ltd, et al. v. Carmichael, etc., et al., 119 S. Ct. 1167 (1999) 1

The trial judge instructs the jury on the law to apply to the facts that it decides. The judge's jury instructions, therefore, take precedence over any testimony by a patent law expert regarding the applicable legal principles. In patent infringement trials, Rule 702 of the FRE permits the trial judge to allow a witness qualified as an expert in patent law to give opinion testimony in that field of expertise. Such testimony is most often restricted to carefully defined areas normally laid out in the pre-trial order, usually after deciding motions in limine seeking to limit the scope of the expert witness' testimony. Prior to giving ultimate opinions on the witness stand, the patent law expert may be allowed to testify in general about some patent law principles, although the judge is likely to circumscribe the expert's testimony to ensure that the jury understands that only the court can instruct it as to the applicable law. Rarely, the trial judge may even allow a patent law expert to give testimony in the form of an opinion or inference that embraces an ultimate issue of fact, such as a date of invention. FRE 704(a). The patent law expert may be required on cross-examination to disclose the underlying facts or data upon which the expert's testimony is based, and neither the attorney-client privilege nor the work product privilege can be relied upon by the party retaining the expert to prevent or limit such disclosure. FRE 705.

IV. Areas in Which Patent Law Experts May Testify

First and foremost, federal judges will usually permit a patent law expert to explain the procedures for obtaining a United States patent, including the form and content of a patent application and the various stages of prosecution. Frequently a patent law expert is also allowed to explain the file history of the particular patent in suit. However, nearly all judges will not permit a patent law expert to give any testimony that will directly, or by inference, attempt to give a particular construction to any claim at issue. Despite FRE 704(a), which abolished the common law prohibition against expert opinions embracing an ultimate issue to be decided by the trier of fact, at the present time, federal district court judges almost universally will not permit a patent law expert to testify that a claim is infringed or not infringed, or that it is invalid. Peripheral testimony on validity by a patent law expert might still be allowed, such as a general explanation of the best mode and enablement requirements, so long as it is general in nature and not specific to the claims in issue.

In a recent case in New Jersey, testifying as the defendant's patent law expert, I was allowed to explain to the jury the long and tortured prosecution history that led to the allowance of the lone claim in suit, highlighting the fact that, after repeated obviousness rejections, the claim to a combination of seven recited elements was allowed only after an eighth element was added by way of amendment. This was critical to the obviousness defense since I also was allowed to explain that, through his patent attorney, the patentee had acquiesced to the obviousness of the combination of elements one through seven. The defendant's technical expert later presented very persuasive testimony to the effect that, in light of the admitted prior art, along with several other prior art publications, it would have been obvious to add the eighth element to the unpatentable combination of elements one through seven.

Federal judges sometimes will permit a patent law expert to give testimony relating to the issue of whether inequitable conduct was perpetrated during the prosecution of the patent in suit. This issue is exclusively an issue for the court to decide, although not infrequently the court will obtain an advisory verdict from the jury. Such testimony is normally limited to an explanation of the duty of candor and good faith and materiality under 37 CFR 1.56, the mechanics of disclosure under 37 CFR 1.97, and the nature and timing of the disclosures in the file history of the patent in suit. In limited cases, a federal judge may permit a patent law expert for the accused infringer to explain in general terms how an intent to deceive may be shown by circumstantial evidence. Usually, the defendant's patent law expert will not be allowed to opine that inequitable conduct has been committed in the particular case at hand. Since the inequitable conduct issue is ultimately decided by the court, greater leeway can be given to the scope of the testimony of a patent law expert in this area. However, the court is usually aware that the jury's decision on the validity and infringement issues should not be unduly prejudiced by the pall of an inequitable conduct allegation.

Other areas in which federal judges are receptive to hearing the testimony of patent law experts include: licensing, reasonable royalty, priority of invention, inventorship, and intervening rights. On the issue of willfulness, the court might permit testimony relating to the usual investigation that a prudent company would pursue in terms of retaining an outside patent attorney and seeking opinion advice. If allowed by the court, technical experts, as opposed to patent lawyers, will typically provide testimony relevant to enablement, anticipation, the teachings of the prior art references, the level of ordinary skill in the art, the differences between the claims and the prior art, obviousness, and the meaning of terms in the claims. Technical experts tend to have advanced college degrees, as well as relevant work and/or academic experience. Typically, CPAs or some other financial experts will provide expert testimony relevant to lost profit and reasonable royalty damage calculations.

V. Selecting a Qualified Patent Law Expert

At trial, the party offering a witness as a patent law expert will go through a short series of questions to qualify the expert, and the court will then ask for any objection from the other side. Without any objection, the court is likely to accept the expert as qualified, provided a suitably impressive level of education and work experience in the patent field has been established. I have seen opposing counsel offer to stipulate during trial that the opposition¿s patent law expert is qualified in order to prevent the jury from hearing his or her impressive credentials. Most judges will still permit the party offering the person as a patent law expert to ask a half-dozen or so questions so that the jury may take the background and experience of the patent law expert witness into consideration.

In selecting a patent law expert, keep in mind that the person should at a minimum be a registered patent attorney with sufficient years and breadth of experience to appear credible to the court and to the jury. This rules out, for example, a fifth year associate patent attorney. Moreover, the patent law expert should have substantial patent prosecution experience and patent litigation experience. Here are a few examples to help you evaluate the credentials of prospective patent law experts.

In a 1990's patent infringement case that was tried in Oregon, the defendant's trial counsel offered as a patent law expert a well known and highly respected law professor who had written a scholarly treatise on patent law. The plaintiff's lawyer did not object to this person testifying as a patent law expert but, on cross-examination showed that the defendant's expert did not possess a science or engineering degree, was not a registered patent attorney, had never written a patent application, had never prosecuted a patent application, had never handled any patent litigation, etc. In terms of scientific background and relevant experience, the defendant's patent law expert could not come close to the credentials of the plaintiff's expert, a seasoned thirty year veteran registered patent attorney with substantial experience in both patent prosecution and patent litigation. The patent attorney was much more comfortable testifying before the jury and was not impeached on cross-examination.

Several years ago, I testified as a patent law expert in a case opposite a former USPTO Commissioner of Patents & Trademarks. On cross-examination, the former Commissioner was forced to admit that he had written only one patent application in the last twenty years (in the early 1980's), and that much of his patent career had consisted of managing patent attorneys in a major corporate patent department followed by a stint at the USPTO running a bureaucracy with thousands of federal civil servants. He also admitted that for the past ten years, his work experience was limited to serving as an expert witness in a handful of patent infringement cases, and further that he had no other patent litigation experience.

Remember that your client will no doubt retain a technical expert, so it is not essential for your patent law expert to have specific educational background or work experience in the field of the invention being litigated. However, be pragmatic in the selection of your candidates. Clearly, a biotech patent attorney with sufficient years and breadth of experience would be best suited to serve as a patent law expert in a patent infringement lawsuit involving a patent on a biotech invention. It can also be advantageous if your patent law expert has substantial patent litigation experience. Preferably, he or she has previously served as an expert on at least three occasions in which testimony was given during deposition or trial. Familiarity with the techniques used in direct and cross-examination is crucial. The expert should be comfortable testifying in front of a jury and should be able to clearly and cogently explain complex patent law concepts at a level that can be readily understood by the average senior in high school. It is also important that your patent law expert have good public speaking skills of the type that are normally developed by giving seminars, trying cases and/or teaching patent law. Also it helps if your patent law expert has published articles or books on patent law subjects, as jurors tend to believe that published authors in the field must be experts.

It is also convenient, and sometimes more economical, if your patent law expert has an office in the same metropolitan area where your office is located or where the case will be tried. Sole practitioner patent attorneys are attractive as potential patent law experts because they are less likely than partners in law firms to have potential or actual conflicts of interest. Draw up a list of possible candidates, and do not forget to ask colleagues for recommendations. Many of your candidates may turn out to be unavailable because of workload, scheduling problems, or conflicts of interest.

It is of paramount importance that you get your patent law expert on board as soon as possible. Your expert will be much better prepared to support your client's case if he or she is not retained on the eve of trial. Most experienced patent law experts will decline eleventh hour requests to put their whole practice on hold so that they can "bone up" as your client's expert.

VI. Working with Your Patent Law Expert

When you first contact a potential patent law expert about his or her availability you should immediately identify the case, including the parties involved, and the general nature of the subject matter so that the candidate can perform an adequate check for actual or potential conflicts of interest. Except as noted below, anything you discuss is not privileged. The candidate will naturally want to know whether he or she is being retained on the side of the patent owner or accused infringer. Once any potential or actual conflicts have been ruled out, you are free to convey additional details, but of course, you should not say that you are seeking an opinion that says X, Y and Z. Give a general neutral explanation of the issues and let him or her know that you will be forwarding background documents, including pleadings, for the potential expert's consideration in formulating some preliminary opinions. Confirm the hourly rate and availability of the potential expert. Does he or she have adequate time available for reviewing voluminous documents, working on the preparation of an expert report, and testifying both at deposition and at trial? Before sending any confidential documents, it will be necessary for your potential expert to review and execute a standard protective order. His or her identity may have to be disclosed, in advance, to opposing counsel.

Once the potential expert has completed a preliminary review of the documents, he or she may verbally indicate that they are "unavailable." You may not want to ask why, because this verbal communication may be an indication that this person cannot support your client's position. You may not want an adverse opinion, even a very preliminary verbal opinion, being discovered by your opposition and used against your client. One safeguard in this situation is to hire the potential expert as a consultant in order to maintain the confidentiality of all your communications. However, you must then hire a different patent attorney as your testifying patent law expert. If your potential expert preliminarily indicates that he or she may be in general agreement with your client's position, send more documents and discuss further details of the case until the candidate feels comfortable that he or she can give the opinion you are seeking. At that point, the candidate will send you a formal engagement letter. Make it clear that your expert will be compensated for his or her time and reasonable expenses. The expert report that is later filed should contain the usual statements that the hourly compensation is not dependent on the substance of your expert's testimony and that the expert has no stake in the outcome of the case.

Bear in mind that any documents exchanged with your designated patent law expert, and all communications with that person, whether written or oral, are not privileged and are fair game for discovery. You will find that most experienced experts keep few notes for this reason. Avoid potentially compromising e-mail communications.

The expert report is typically drafted by trial counsel, but it reflects opinions previously stated orally by the patent law expert in a series of conversations with trial counsel. The expert report will usually go through a number of revisions, each of which is discoverable unless the parties to the lawsuit agree otherwise. The patent law expert's report must be filed with the court by a prescribed deadline, and it may also be necessary for your expert to prepare a rebuttal to the opposition's expert report. Care should be taken to fully comply with Federal Rule of Civil Procedure 26(a)(2) in preparing expert reports. Failure to prepare and timely serve a thorough report could result in the trial judge refusing to permit testimony in certain areas in applying the Daubert and Kumho standards against the report. Do not plan on presenting any opinions at trial that are not covered in your expert's report(s).

VII. What Your Patent Law Expert Can Expect from Opposing Counsel

A few years ago, a friend and colleague of mine, who was an excellent patent attorney with many years of prosecution experience but no patent litigation experience, decided to take a stab at patent law expert witness work. He was retained by a law firm representing an accused infringer in a patent lawsuit. The defendant's trial attorney did not have much patent litigation experience. After my friend's expert witness report was produced, his deposition was taken. He was torn apart in the deposition by a very experienced patent attorney representing the patent owner. My friend had overreached in some areas of his expert report and did not fully appreciate what it meant to be able to justify his opinions under skillful cross-examination. He ended up withdrawing three of his six opinions during his deposition.

I have, on occasion, seen a patent law expert challenged on the basis that he or she lacks technical training and/or experience in the specific field of invention. However, it is not necessary for the expert to have specialized knowledge in the technology at hand. The patent law expert can testify that he or she has relied upon the reports, opinions, and testimony of technical experts in formulating the patent law opinions that have been given. Juries readily accept the different roles of patent law and technical experts and they appreciate the candid admission by the patent law expert that the PhD scientists or engineers are the experts in the technology involved in the lawsuit.

Your patent law expert should not assume that opposing trial counsel will ask every question at deposition that he or she intends to ask a trial. Since your expert's report is "cast in stone" so-to-speak, opposing counsel can safely withhold questions for surprise cross-examination at trial where there are clear misstatements of patent law or procedure in your expert's report. Often, the most effective cross-examination will be a short quick series of questions pointing out the misstatements of law or procedure, however minor, in the expert's report. You would be surprised how many errors slip into the reports of patent law experts. For example, in one case in which I was retained, the opposing expert erroneously stated that the specification must be enabling to a person of ordinary skill in the art to which the invention pertains. The modifying term "ordinary" does not appear in the enablement clause of 35 U.S.C. Sec. 112, first paragraph; rather, it appears only in the non-obvious requirement of 35 U.S.C. Sec. 103(a). When confronted with this misstatement at trial, the expert might attempt to argue that there is no difference. However, skillful trial counsel will ask for a simple "yes" or "no" answer on whether the enablement clause of 35 U.S.C. Sec. 112 expressly recites the term "ordinary." A jury will tend to look with some disfavor on a supposed patent law expert who does not seem to know the fine points of patent law, however arcane they might be. In the final analysis, your patent law expert must be able to defend the opinions given in his or her expert report when under the hostile fire of cross-examination.

VIII. Conclusion

Patent law experts continue to play an important role in patent litigation, although their relative significance varies from case to case depending upon the issues involved and the judge's willingness to hear their testimony on a variety of different issues. Good patent trial advocacy requires considerable care in the proper selection and utilization of patent law experts.
They are, however, just one piece of the larger framework of a successful patent litigation strategy.

About the Author:

Michael H. Jester is a registered patent attorney, who maintains a solo practice in Coronado, California, specializing in patent prosecution and expert witness testimony. He holds B.S. and J.D. degrees from the University of California and is a member of the bars of California and the District of Columbia.