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?