Prosecution history - as relevant as any inventor evidence?

Readers interested in patent law will be familiar with last summer's decision of the UK Supreme Court in Actavis v Eli Lilly [2017] UKSC 48 This has raised a number of issues, including whether the Supreme Court decision opens the door to greater use of the file history in the UK.  Taly Dvorkis of A&O enters into the debate, examining the differences in US and UK law, and queries whether it is linked to inventor evidence:
The inventor Kat taking centre stage
"At the November UCL debate "Equivalents: K = Na. Is the genie out of the bottle?" (reported on IPKat here and here), U.S. Court of Appeals for the Federal Circuit Judge Kathleen O'Malley expressed the view that had the Actavis v Lilly case come before a US court, the result may have been different, in light of the established doctrine of prosecution history estoppel, whereby concessions made by the patentee during prosecution limit the scope of equivalence that can be sought.

Prosecution history estoppel has not been applied in English proceedings, and it remains to be seen whether that will change in light of Actavis v Lilly. The judgment does not completely discount the relevance of the prosecution file but finds it is appropriate to take "a skeptical, but not absolutist, attitude" towards it.  The judgment reiterates the oft-repeated words of Lord Hoffman in Kirin-Amgen [2005] RPC 9: “The courts of the United Kingdom, the Netherlands and Germany certainly discourage, if they do not actually prohibit, use of the patent office file in aid of construction. There are good reasons: the meaning of the patent should not change according to whether or not the person skilled in the art has access to the file and in any case life is too short for the limited assistance which it can provide.”

Do those jurisdictions that take into account the contents of the prosecution file (such as the US) do so because there it is assumed that the skilled person would also have examined the file? That is unlikely. Rather, I think the difference between the UK and the US approaches is more fundamental - it is the difference in how all inventor evidence is treated.

Patent litigation in the UK has no need for the patentee. It is becoming increasingly difficult to obtain disclosure of inventor documents. What the inventor thought was invented, the work done to get there, and how the inventor understood the state of the art are not relevant - rather, the scope of patent protection is whatever the skilled person would have understood it to be. There is no need for evidence from the patentee (who may not be a skilled person but may have extraordinary skill in the art).

In the US, the patent scope is similarly determined by reference to the skilled person; however, the patentee plays a greater role in the litigation. Much of the discovery revolves around the patentee, including disclosure of the inventor’s documents and the taking of inventor depositions. Often the first witness to testify at trial - whether before a judge or jury - is the patentee, telling his invention story. The inventor's views and corresponding documents may be used to try and define claim scope, obviousness, novelty, and the state of the art.

It is not surprising, in this framework, that evidence showing a patentee’s back-and-forth with the patent office could have significance in narrowing the scope of protection. Meanwhile in the UK regime where evidence from inventors is not relied upon, there has been no need to rely upon the file history or apply estoppel. The underlying rationale is not only that “life is too short” - rather, as with all evidence pertaining to the patentee, it isn’t needed. Or is it?

Even before Actavis v Lilly, a skilled person had to take into account the patentee’s intent when applying the third Improver question, which asks: “Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention?” The patentee’s intentions remain at the root of the third question as reformulated by Actavis v Lilly: “Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention?”
To assess equivalence, a patentee’s intentions need to be known. As mentioned at the UCL debate, those intentions may be gauged from the language of the specification, such as when the patentee specifically disavows a potential equivalent. But the intentions can also be learned from the file history, as the judgment acknowledges.

Actavis v Lilly demonstrates there may be room to consider the file history, and by extension, evidence from the patentee. It remains to be seen whether the court will apply prosecution history estoppel to limit equivalence, but if it does - what’s next? Would other inventor evidence be taken into account? That seems unlikely, given the general trend to limit disclosure."

These obervations on inventor evidence resonate with this Guestkat's experience in the UK. What do readers think?
Prosecution history - as relevant as any inventor evidence? Prosecution history - as relevant as any inventor evidence? Reviewed by Eibhlin Vardy on Friday, January 19, 2018 Rating: 5


  1. One of the great strengths of English law is that its fact-finding procedures ought to keep people (parties, witnesses) "honest". So too can the evidence of the file history.

    For example, imagine deciding a case on the evidence of experiments, without inspection and cross-examination.

    But it's all a question of "balance". Give zealous litigators an inch of freedom to adduce more evidence (say: the PTO file wrapper) and they will bring a bus load of it, to complicate the case.

    Strict case management is needed, by a court experienced enough to know when the wool is being pulled over its eyes. I happen to think that the patents courts of England are unique in all the world for the wisdom and pragmaticism of its judges, coupled with totally flexible fact-finding procedures which the parties can use to flush out dissembling and lack of good faith. Where else but in England can parties in dispute get a better and quicker written roadmap of the merits of the case?

    Elsewhere there is not enough wise case management, or too much "flexibility" and so loss of legal certainty.

    But what do other readers think?

  2. Once you have a doctrine of equivalents you must have file wrapper estoppel and amendments (

    What you have lost by amendment cannot be regained by doctrine of equivalents. It cannot be any other way for the system to make sense. We now need to accept the situation and start to develop our own 'Festo doctrine' of how the scope of a claim is affected by past amendments. Otherwise a lot of injustice will occur.

  3. Older readers may recall that, before the UK's 1977 Patents Act came into force, very little of the prosecution file was open to public inspection (the provisional application, priority document and its translation (if any), the complete application as filed, the patent as granted, a list of any documents cited during prosecution, and not much else). However, the full file could be inspected by a judge if the patent came to court. Thus I would think that the prosecution history must have been taken into account in such cases, otherwise what purpose would there have been in the judge inspecting the file?

  4. Great comments from both Festo and Ron. The USA has a slew of "doctrines" downstream of its "Doctrine of Equivalents", for example, "re-capture" and "ensnarement", to minimise the legal uncertainty and injustice entrained with the DoE. But the judges in Europe are aware of all this and will keep things simpler. At a conference in Germany some years ago, Robin Jacob was heard to say:

    You can learn a lot from the Americans. watch carefully what they do, then make sure you don't repeat their mistakes.

    The Activis facts were very special. I predict that the DoE will hardly ever succeed in England.

  5. O'Malley surmises that Activis would have gone the other way, in the USA. well yes, of course. Because the American DoE is very different from the one in Activis.

    What Neuberger did was to leave claim construction undisturbed. No change there. An infringement by equivalent is by an act that falls outside the scope of the claim, properly construed. Unlike in America.

    To construe a claim in England, there is no need to take account of the Patent Office file. Nor is there now. If you do it anyway, in Activis, you find that limitation to Na was because of poor drafting and Art 123(2) not the prior art.

  6. Once again, I wander upon a series of comments involving those of MaxDrei and have to wonder if he realizes what he is posting.

    Contrast the last comment of "Nor is there now." with his first post of "So too can the evidence of the file history."

    Which is it? Do you have a clue?

  7. Which is it? When judging infringement by equivalent, recourse to the wrapper might be a help. For construing the claim though, not.

  8. The Same Previous AnonymousMonday 22 January 2018 at 11:32:00 GMT

    That makes no sense, maxdrei - I leave it to you to figure out why.

  9. It makes no sense to "The US Anon". How about readers from the UK?

  10. Interesting MaxDrei that you are treating construing the claim very differently from judging infringement. I broadly agree, that claim construction (i.e. without DOE) can be done without looking at the prosecution history, and DOE analysis can only be done using knowledge of the potential infringement and that will be assisted by the prosecution history. DOE analysis is going to be very fact specific and require a very good understanding of how the claim ended up as it did and how it relates to the inventive concept. Everything that helps that analysis should be available and used, and perhaps even documents from discovery to establish the intentions of all the relevant parties. It is important to come up with a reason as to why the patentee deserves the DOE scope, and equally to understand why it is not unfair for a potential infringer to be caught by the DOE scope.

  11. Thanks for that, Acoom. But it's not just me. I got the "interesting" idea from Lord Neuberger's opinion in Activis. He started it, not me!


All comments must be moderated by a member of the IPKat team before they appear on the blog. Comments will not be allowed if the contravene the IPKat policy that readers' comments should not be obscene or defamatory; they should not consist of ad hominem attacks on members of the blog team or other comment-posters and they should make a constructive contribution to the discussion of the post on which they purport to comment.

It is also the IPKat policy that comments should not be made completely anonymously, and users should use a consistent name or pseudonym (which should not itself be defamatory or obscene, or that of another real person), either in the "identity" field, or at the beginning of the comment. Current practice is to, however, allow a limited number of comments that contravene this policy, provided that the comment has a high degree of relevance and the comment chain does not become too difficult to follow.

Learn more here:

Powered by Blogger.