UK: Markman, Warner-Jenkinson And Festo - Implications For The European Practitioner

Last Updated: 24 October 2002
Article by Paul Cole

How US patent claims should be interpreted has been the subject of intense debate, and has been considered by the US Supreme Court three times since 1996. Following the recent decision of the Supreme Court in Festo Corporation v Shoketsu Kinzoku1 the rules have hopefully now become more settled. The decisions in the above three cases should be considered together, and the purpose of this article is to summarise the main points that can be gleaned from them and to consider their implications for European practitioners in their day-to-day work of drafting applications and providing instructions to their colleagues in the USA. Of course, where there is any difficulty, or where a legal opinion is required, there is no substitute for the advice of a US practitioner.

At issue in Markman2 was whether the construction of a patent, including terms of art within the claims was for the court to decide, or whether it should be decided by a jury, the right to a jury trial in any action where the value in dispute exceeds $20 being preserved by US Constitution, seventh amendment. The Court decided that the construction of patents, as of other written documents, should be left to the judge since common law practice at the time of framing of the US Constitution and early cases from England both showed that judges, not juries, construed terms in patent specifications, and because this which a task that a judge, from his training and discipline, was in the better position to perform. Following that decision, pre-trial Markman hearings to construe the patent’s claims following motions by defendants for summary judgment have become a routine feature of infringement trials and now account for a major part of the work of the CAFC3.

The continued existence of the doctrine of equivalents was challenged in both Warner Jenkinson v Hilton Davis4 and in Festo. In both cases it was held not to have been rendered obsolete by the entry into force of 35 USC 103 in 1952. In Festo the Court explained that:

"The language in the patent claims may not capture every nuance of the invention or describe with complete precision the range of its novelty. If patents were always interpreted by their literal terms, their value would be greatly diminished. Unimportant and insubstantial substitutes for certain elements could defeat the patent, and its value to inventors could be destroyed by simple acts of copying. For this reason, the clearest rule of patent interpretation, literalism, may conserve judicial resources but is not necessarily the most efficient rule. The scope of a patent is not limited to its literal terms but instead embraces all equivalents to the claims described. See Winans v. Denmead, 15 How. 330, 347 (1854).

It is true that the doctrine of equivalents renders the scope of patents less certain. It may be difficult to determine what is, or is not, an equivalent to a particular element of an invention. If competitors cannot be certain about a patent’s extent, they may be deterred from engaging in legitimate manufactures outside its limits, or they may invest by mistake in competing products that the patent secures. In addition the uncertainty may lead to wasteful litigation between competitors, suits that a rule of literalism might avoid. These concerns with the doctrine of equivalents, however, are not new. Each time the Court has considered the doctrine, it has acknowledged this uncertainty as the price of ensuring the appropriate incentives for innovation, and it has affirmed the doctrine over dissents that urged a more certain rule."

The Court explained both in Warner-Jenkinson and in Festo that the doctrine of equivalents was settled law, and that:

" … the lengthy history of the doctrine of equivalents strongly supports adherence to our refusal in Graver Tank to find that the Patent Act conflicts with that doctrine. Congress can legislate the doctrine of equivalents out of existence any time it chooses. The various policy arguments now made by both sides are thus best addressed to Congress, not this Court."

However, in Warner-Jenkinson, the court responded to concerns that the doctrine of equivalents had taken on a life of its own, unbounded by the patent claims, which conflicted with the definitional and public notice function of claims. It concluded that the doctrine was applicable to the individual elements in a claim, and not to the claim as a whole, and that a claimed element should not be eliminated in its entirety. The essential inquiry was whether the accused product or process contained elements identical or equivalent to each claimed element of the invention:

"An analysis of the role played by each element in the context of the specific patent claim will thus inform the inquiry as to whether a substitute element matches the function, way, and result of the claimed element, or whether the substitute element plays a role substantially different from the claimed element."

The doctrine of equivalents is applicable equally to claims that were allowed unamended and to claims that were rewritten during prosecution. As the court explained in Festo:

"By amending the application, the inventor is deemed to concede that the patent does not extend as far as the original claim. It does not follow, however, that the amended claim becomes so perfect in its description that no one could devise an equivalent. After amendment, as before, language remains an imperfect fit for invention. The narrowing amendment may demonstrate what the claim is not; but it may still fail to capture precisely what the claim is…The amendment does not show that the inventor suddenly had more foresight in the drafting of claims than an inventor whose application was granted without amendments having been submitted. It shows only that he was familiar with the broader text and with the difference between the two. As a result, there is no more reason for holding the patentee to the literal terms of an amended claim than there is for abolishing the doctrine of equivalents altogether and holding every patentee to the literal terms of the patent."

How, then, could the law establish the most appropriate balance between the competing interests of protection for the patentee and certainty for the public? In Festo, the Court was provided with a range of options advanced by the parties and by various amici:

  • There should be an absolute bar on coverage of equivalents where a restriction had been introduced into a claim during prosecution because such restriction was a disclaimer. This "bright-line" approach which had been adopted by the CAFC in Festo was supported by a number of major US companies including IBM, Eastman Kodak, Ford, Intel, Cypress Semiconductor Corporation and United Technologies Corporation.
  • There should be a flexible bar that denied coverage of otherwise patentable subject matter only where it had been clearly and unmistakably surrendered by the patentee. This approach was supported, amongst others, by the American Intellectual Property Law Association.

  • There should be a foreseeable bar which permitted equivalents to be covered unless the limiting effect of amended language with respect to an accused device would have been foreseeable at the time of the amendment to a reasonable person skilled in the art. The foreseeable bar was said to avoid each ‘parade of horribles’ put forward by respective opponents of the flexible bar and the absolute bar, while simultaneously giving effect to the policy considerations advanced by their respective advocates. Thus a patentee could argue for an extended meaning by showing that the alleged infringement was a later development or that a person of ordinary skill in the art could not reasonably have drafted a patent claim that literally encompassed the alleged equivalent. That approach was advocated by IEEE and by the US Government.

The Supreme Court adopted a foreseeability standard and concluded that the claims could cover equivalents that were unforeseeable or that for some other reason the patentee could not reasonably be expected to have described. Since the patentee has, as explained above, the same level of foresight at the time of drafting the application and at the time of submitting amendments, this standard implicitly applies equally to unamended claim language and to claim language that has been amended during prosecution.

The doctrine of prosecution history estoppel requires the claims of a granted patent to be interpreted in the light of events during prosecution so that subject matter that has been surrendered cannot be recaptured. In Festo the court decided that any narrowing amendment made to satisfy a requirement of the Patent Act could give rise to an estoppel. However, the purpose of the estoppel doctrine was to hold the applicant to the representations made during prosecution and the inferences that might reasonably be drawn from any amendment that had been made. Reading the Warner-Jenkinson and Festo decisions together shows that there is a rebuttable presumption that estoppel applies, subject to the following rules:

  1. The onus is also on the patentee to prove that the amendment could not reasonably be viewed as surrendering a particular equivalent, for example because:
    • the equivalent was unforeseeable at the time of the application or amendment, or
    • the reason for the amendment was irrelevant to the equivalent in question; or
    • there was some other reason why the patentee could not reasonably have been expected to have covered the equivalent in question.

  2. If the patentee is unable to explain the reasons for an amendment that narrows an element, then estoppel bars the application of the doctrine of equivalents and the patentee is presumed to have surrendered all subject matter between the broader and the narrower language.

So what can we in Europe do in response to the decisions culminating in Festo and how should we strengthen or alter our practice? It is suggested that if we follow four simple steps, which should already be part of our routine practice, we should be able to send applications and subsequent instructions for amendment to our US colleagues whilst avoiding our clients ending up with unduly narrow claims. These steps are:

  • At the time of filing to have discussed with our clients the range of foreseeable equivalents to the embodiments or examples that have been provided and to check that the claim language covers those equivalents. This may require providing definitions of the technical terms used in the claims to provide "intrinsic" evidence of the meaning of those terms for use at a possible future Markman hearing, and the inclusion of further embodiments or examples to provide support for the range of equivalents that it is intended to cover. European practitioners used to problem/solution analysis should have little difficulty in arriving at broad claim language, at least in the main independent claims, but the importance of definitions and additional embodiments in providing the required "notice" to the public has received less publicity in Europe than its importance demands.

  • During prosecution check for equivalents lying outside the scope of the claims as proposed to be amended. The US Examiner’s well-meaning suggestion that patentable subject matter could be found e.g. if claim 1 were combined with claims 14 and 23, or that he would allow the claim if limited to the use of anhydrous solvents, though inexpensive to follow may not be wise. It is not just a question of what it costs to obtain a granted patent but also what it could cost to have a patent that is unenforceable. As Festo makes clear, the doctrine of equivalents is not an aid for patentees who cut corners during prosecution and introduce limitations they later regret.

  • Ensure that the client or inventor understands the proposed amendment amendment, and has appreciated what subject matter is being given up and what is not. The need for the attorney to work closely with the client in deciding on claim scope and language is emphasized by the Festo decision.
  • Explain the reasons that have prompted amendment, and the intentions underlying the amendment, emphasizing where appropriate the limited nature of those reasons and intentions. Hopefully that will avoid third parties or a court giving the claim an unintentionally narrower meaning when the claims are read, or mis-read.

The Festo opinion should serve as a reminder that the patent specifications that we prepare and the prosecution files that we generate have to be fit to place before a judge. Those who have been involved in litigation will appreciate just how high a standard that implies, and what severe criticism and/or fatal consequences can follow from failing to meet that standard. Festo demonstrates that courts may be prepared to help patentees in unforeseeable difficulty, but that they will have little sympathy for patentees who come with ill-prepared specifications and claims with limitations that it could have been foreseen were unnecessary. Notwithstanding the express inclusion of equivalents in the proposed amended Protocol to Article 69 EPC, the foreseeable standard adopted by the Supreme Court is bound to have influence, explicitly or tacitly, in Europe and elsewhere. Those who criticise the costs of patent drafting and prosecution (usually in the name of the small inventor) should reflect on the effort and skill needed to marshal all the relevant facts, explain them in a coherent manner and provide a clear definition of the rights to be protected. They would then appreciate that legally effective patents, like other legal documents cannot come cheap.

1 Opinion handed down 28 May 2002

2 Opinion handed down 23 April 1996

3 See, for example the CAFC decisions in Schering Corporation and Biogen v Amgen Inc decided 1 August 2000 (defendants succeeded), Phillips Petroleum v Huntsman Polymers decided 22 September 1998 (meaning of "block copolymer"; defendants succeeded) and Pitney Bowes v Hewlett Packard decided 23 June 1999 (plaintiffs’ appeal allowed) are examples amongst very many such decisions.

4 Opinion handed down 3rd March 1997

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.

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