News from Abroad: The Regretful Patentee -- The Re-Emergence of File Wrapper Estoppel & Equivalence in the UK

by McDonnell Boehnen Hulbert & Berghoff LLP


ActavisFor the best part of 10 years, since the judgment of Lord Hoffmann in Kirin-Amgen v Hoescht Marion Roussel[1], it has been widely assumed that there is no file wrapper estoppel in the UK and no doctrine of equivalents either.  Both these assumptions are thrown into doubt by the Patent Court's decision in Actavis v Eli Lilly[2].  The judge, Mr Justice Arnold, held that the court should not shut its eyes to the prosecution file but should ensure a patentee did not abuse the system by accepting narrow claims during prosecution and then argue for a broader construction in a subsequent infringement action.  The judge also applied the more or less defunct Improver or Protocol Questions[3] in a manner that potentially opens the door to a doctrine of equivalence in all but name.

Use of the File Wrapper

In Kirin-Amgen, Lord Hoffmann said that there were good reasons why the German and English courts discouraged, if not actually prohibited, the use of patent office files in aid of the construction of claims.  The reasons included that the meaning of a patent does not change depending on whether a party has access to the office file or not and anyway the file may reflect no more than a patentee's desire to get the patent granted quickly without further argument with the examiner.  In short, it was a difficult and likely unproductive exercise to use the file wrapper to try to work out what the patentee meant by a claim's terms.

Taking the hint, parties and the courts made little use of file wrappers in subsequent cases with Sir Robin Jacob observing in Eli Lilly v Human Genome Sciences[4] that he was not confident it was legitimate to do so even though the UK courts had yet to decide the matter conclusively.  Going further, Mr Justice Floyd in Qualcomm v Nokia[5] warned that it was positively counterproductive to be referred to prosecution documents as it alerted the tribunal to the fact that there might be something to be said for the alternative construction.

Doctrine of Equivalents

While Lord Hoffmann considered that Article 69 of the European Patent Convention firmly shut the door on any doctrine which extended protection outside the claims, he acknowledged that equivalence could be an important part of the background that would affect the skilled person's understanding of a claim.  This was consistent with Article 2 of the Protocol on the Interpretation of Article 69, which states that, in balancing the literal and purposive construction of a patent's claims, due account should be taken of "any element which is equivalent to an element specified in the claims".  However, he doubted the usefulness of the Improver Questions in reaching a purposive construction saying that there was only one compulsory question:  what would a person skilled in the art have understood the patentee to have used the language of the claim to mean?

Following this decision, the Improver Questions have seldom been used in UK patent actions.  In Smith & Nephew v Convatec Technologies[6] it was even questioned whether a 1992 decision on infringement of a numerical limitation would have been decided the same way following Kirin-Amgen as it had been using the Improver Questions.

The Actavis v Eli Lilly Decision

LillyThe Actavis case concerned Eli Lilly's European patent protecting its cancer treatment, Alimta.  The patent claims the active ingredient, pemetrexed disodium, in combination with vitamin B12 and, optionally, a folic protein binding agent.  Actavis sought declarations that its proposed generic version of Alimta, which would contain one of pemetrexed diacid, pemetrexed dipotasium or pemetrexed dimethamine, did not infringe.  As Actavis was not challenging validity, it was allowed to seek declarations of non-infringement under the French, Italian and Spanish designations of the patent as well as the UK designation.

In his judgment, Mr Justice Arnold carefully reviewed the case law on both use of file wrappers and the doctrine of equivalence.  On the latter, he identified three main classes of case in which patentees resort to arguments on equivalence, namely where:

(i)       the patent has been poorly drafted (as in the Improver case);

(ii)      technology has moved on significantly since the patent was filed (as in Kirin-Amgen); and

(iii)     the patent regrets a decision taken during the course of prosecution.

The Actavis case was a clear example of the third category.  Eli Lilly had attempted to broaden its claims in prosecution to cover "pemetrexed", failed and accepted the narrower claims to pemetrexed disodium.  It had reserved the right to file a divisional application, but did not do so.  It clearly now wished it had broader claims in order to catch Actavis on infringement.  But there was "no reason why the law should be sympathetic to the patentee", which not only had the benefit of skilled professional advice but also had the opportunity to appeal against adverse decisions by patent examiners.  Further, allowing examiners' decisions effectively to be overturned by the courts on claim construction would undermine their important role.  Against this background, Mr Justice Arnold made use of the prosecution history as one of several reasons why Eli Lilly's broad construction, that pemetrexed disodium encompassed other salts because the important pemetrexed anion was present irrespective of the cation used, should be rejected.

He also used the Improver Questions, partly because there was no dispute that the alleged infringement was not within the primary, literal meaning of the claim and partly because the parties used them for consistency in their submissions on the non-UK designations.


Mr Justice Arnold observed that the US has a doctrine of equivalence and a doctrine of file wrapper estoppel to counterbalance it.  While following prior case law, the UK had neither, file wrapper estoppel is back albeit only in the case of the regretful patentee.  Even then, as Arnold J warned, the courts should be cautious using the prosecution history only when it is short, simple and shows clearly why the claims are in their granted form and not broader.

As regards equivalence, using the Improver Questions having held that there is plainly no literal infringement comes very close to Lord Hoffmann's description of the US approach in Kirin-Amgen as being "to adhere to literalism in construing the claims and evolve a doctrine which supplements the claims by extending protection to equivalents".  Even if not explicitly recognised as a doctrine of equivalence, the decision may therefore lead to a resurrection of the Improver Questions by patentees effectively arguing just that.

* Ralph Cox is a Partner with Fasken Martineau LLP (London, UK)
** Simon Patrick Spink is a Senior Associate with with Fasken Martineau LLP (London, UK)

[1] [2005] RPC 9

[2] [2014] EWHC 1511 (Pat)

[3] From Improver v Remington Consumer Products [1990] FSR 181 - in brief, as guidance on arriving at a purposive construction of a claim, the Questions ask whether a variant has a material effect on the way an invention works, whether this was obvious at the patent's publication date and whether strict compliance with the primary meaning of the claim is nonetheless essential.

[4] [2013] RPC 22

[5] [2008] EWHC 329 (Pat)

[6] [2013] EWHC 3955 (Pat)


DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

© McDonnell Boehnen Hulbert & Berghoff LLP | Attorney Advertising

Written by:

McDonnell Boehnen Hulbert & Berghoff LLP

McDonnell Boehnen Hulbert & Berghoff LLP on:

Readers' Choice 2017
Reporters on Deadline

"My best business intelligence, in one easy email…"

Your first step to building a free, personalized, morning email brief covering pertinent authors and topics on JD Supra:
Sign up using*

Already signed up? Log in here

*By using the service, you signify your acceptance of JD Supra's Privacy Policy.
Custom Email Digest
Privacy Policy (Updated: October 8, 2015):

JD Supra provides users with access to its legal industry publishing services (the "Service") through its website (the "Website") as well as through other sources. Our policies with regard to data collection and use of personal information of users of the Service, regardless of the manner in which users access the Service, and visitors to the Website are set forth in this statement ("Policy"). By using the Service, you signify your acceptance of this Policy.

Information Collection and Use by JD Supra

JD Supra collects users' names, companies, titles, e-mail address and industry. JD Supra also tracks the pages that users visit, logs IP addresses and aggregates non-personally identifiable user data and browser type. This data is gathered using cookies and other technologies.

The information and data collected is used to authenticate users and to send notifications relating to the Service, including email alerts to which users have subscribed; to manage the Service and Website, to improve the Service and to customize the user's experience. This information is also provided to the authors of the content to give them insight into their readership and help them to improve their content, so that it is most useful for our users.

JD Supra does not sell, rent or otherwise provide your details to third parties, other than to the authors of the content on JD Supra.

If you prefer not to enable cookies, you may change your browser settings to disable cookies; however, please note that rejecting cookies while visiting the Website may result in certain parts of the Website not operating correctly or as efficiently as if cookies were allowed.

Email Choice/Opt-out

Users who opt in to receive emails may choose to no longer receive e-mail updates and newsletters by selecting the "opt-out of future email" option in the email they receive from JD Supra or in their JD Supra account management screen.


JD Supra takes reasonable precautions to insure that user information is kept private. We restrict access to user information to those individuals who reasonably need access to perform their job functions, such as our third party email service, customer service personnel and technical staff. However, please note that no method of transmitting or storing data is completely secure and we cannot guarantee the security of user information. Unauthorized entry or use, hardware or software failure, and other factors may compromise the security of user information at any time.

If you have reason to believe that your interaction with us is no longer secure, you must immediately notify us of the problem by contacting us at In the unlikely event that we believe that the security of your user information in our possession or control may have been compromised, we may seek to notify you of that development and, if so, will endeavor to do so as promptly as practicable under the circumstances.

Sharing and Disclosure of Information JD Supra Collects

Except as otherwise described in this privacy statement, JD Supra will not disclose personal information to any third party unless we believe that disclosure is necessary to: (1) comply with applicable laws; (2) respond to governmental inquiries or requests; (3) comply with valid legal process; (4) protect the rights, privacy, safety or property of JD Supra, users of the Service, Website visitors or the public; (5) permit us to pursue available remedies or limit the damages that we may sustain; and (6) enforce our Terms & Conditions of Use.

In the event there is a change in the corporate structure of JD Supra such as, but not limited to, merger, consolidation, sale, liquidation or transfer of substantial assets, JD Supra may, in its sole discretion, transfer, sell or assign information collected on and through the Service to one or more affiliated or unaffiliated third parties.

Links to Other Websites

This Website and the Service may contain links to other websites. The operator of such other websites may collect information about you, including through cookies or other technologies. If you are using the Service through the Website and link to another site, you will leave the Website and this Policy will not apply to your use of and activity on those other sites. We encourage you to read the legal notices posted on those sites, including their privacy policies. We shall have no responsibility or liability for your visitation to, and the data collection and use practices of, such other sites. This Policy applies solely to the information collected in connection with your use of this Website and does not apply to any practices conducted offline or in connection with any other websites.

Changes in Our Privacy Policy

We reserve the right to change this Policy at any time. Please refer to the date at the top of this page to determine when this Policy was last revised. Any changes to our privacy policy will become effective upon posting of the revised policy on the Website. By continuing to use the Service or Website following such changes, you will be deemed to have agreed to such changes. If you do not agree with the terms of this Policy, as it may be amended from time to time, in whole or part, please do not continue using the Service or the Website.

Contacting JD Supra

If you have any questions about this privacy statement, the practices of this site, your dealings with this Web site, or if you would like to change any of the information you have provided to us, please contact us at:

- hide
*With LinkedIn, you don't need to create a separate login to manage your free JD Supra account, and we can make suggestions based on your needs and interests. We will not post anything on LinkedIn in your name. Or, sign up using your email address.