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Getting Priority Right in Europe

A recent high-profile post-grant opposition case at the European Patent Office (EPO) highlights the need for patent Applicants and their agents to tread carefully when considering where the “rights to priority” from earlier applications actually lie.

The right to priority

When a patent application (or utility model) is first filed, a “right to priority” is then established. This means that, effective for up to one year from the date of filing of the first application, a subsequent application can be filed claiming priority from the initial application (or now a “priority application”). The subsequent application, providing it is for the same invention, is considered to have the effective date of filing of the first (“priority”) application for examination purposes, effectively extending the filing date of the second application by up to a year. This gives applicants protection against prior art filed or published in that priority year, often including their own publications.

The “right of priority” derived from the first application is in itself a substantive property right, legally separate and transferrable from the “property rights” of the first application. This is outlined in in the European Patent Convention (Articles 87 to 89, with Rules 52 to 54). Especially key is Art. 87(1) of the European Patent Convention (EPC):

Any person who has duly filed, in or for

(a) any State party to the Paris Convention for the Protection of Industrial Property or

(b) any Member of the World Trade Organization,

an application for a patent, a utility model or

a utility certificate, or his successor in title, shall enjoy, for the purpose of filing a European patent application in respect of the same invention, a right of priority during a period of twelve months from the date of filing of the first application.” (emphasis added by the author)

This is almost identical to Article 4A(1) of the Paris Convention. The key, highlighted, point is that it is prior to filing, (for the purpose of filing), that the above discussed right to priority exists. Thus, the right existed before filing, and must be considered before filing. This can have wide reaching legal ramifications.


The fact that the “right of priority” is in itself legally separate and transferrable from the property right to the first application means that it must be assigned separately as such. Thus, it is important to keep track of these rights when filing any subsequent applications which claim priority to an earlier application. Agents dealing with filing need to be asking and checking with the applicants “Does the applicant of the new/subsequent application actually possess a right of priority?”

This answer is simple “yes” when the applicants don’t change from the priority application to the subsequent application. However, when there is a change, then in order to comply with at least the European Patent Convention, then the rights to priority must be lined up (i.e. assigned) prior to the application being made. When there has been a change in applicant, the application must come from the original applicant’s “successor in title”, i.e. a person or legal entity who has had the priority right from the earlier application assigned to them.


Some recent decisions by the EPO technical Board of Appeal (T 1103/15, T 1201/14 and T 0517/14) confirm that assignment must be shown to be executed prior to the filing of the subsequent application (typically a PCT application claiming priority to a national phase application). A good summary is provided in EPO technical Board of Appeal case T 1201/14:

The successor in title with respect to the right to claim priority from a first application according to Article 87(1) EPC 1973 must prove that it indeed owned,

(i) before the filing of the later European application,

(ii) the right of priority relating to the first application for the purpose of filing the later European application claiming that priority.

This is typically proven in the form of a contract, which can be filed at the EPO as evidence that the right was transferred, with declarations from both parties that they were satisfied that the rights were transferred. The EPO does not accept that assignments of applications automatically include assignment of priority too (T 1201/14), and one cannot retroactively assign the right of priority, which contravenes Article 87(1) EPC 1973.

“… It has to be proven that the right of priority derived from the first application and claimed for the later European application was indeed transferred, before the filing date of the later European application, by the applicant of the first application to its successor in title, in accordance with specific formal requirements” (T 1201/14, emphasis added by the author)

This particular legal issue was key in a recent high-profile post-grant opposition case at the EPO, where the EPO revoked a very high profile CRISPR/Cas9 patent due to an invalid priority claim.


A case study –  Broad Institute CRISPR/Cas9 patent EP 2 771 468 revocation


CRISPR/Cas9 gene editing technology (CRISPR) is a group of technologies allowing users to edit an organism’s DNA. The technology is relatively new (with non-bacterial organism gene editing only thought possible around 2012 – although exactly when, is highly contentious!), but it is already having huge impact in gene editing research and development, with high profile studies hitting the mainstream media, yearly discussion of a possible Nobel prize, and hundreds of millions of dollars of investment in companies seeking to commercialise the technology.

CRISPR has been part of highly contentious patent battles in the United States between the Broad Institute and the University of California (UC), Berkeley, with a high-profile U.S. Patent Trial and Appeal Board (PTAB) case on-going. It seems that The Broad Institute is winning the CRISPR patent battle in the U.S., as in February 2017 PTAB ruled in Broad’s favour regarding their early priority date CRISPR patent. UC Berkeley’s appeal hearing is on-going, with hearings set for May and June 2018.

However, the situation currently looks set to be very different in Europe, and recently the issue of priority assignments found itself at the centre of the legal battle.

The patent in question

The Broad Institute’s patent EP 2771468 granted 11 February 2015 and claims priority from 12 US provisional applications, with a key earliest priority date of 12 December 2012. The European patent is a national filing of PCT application PCT/US2013/074819. As expected in such a highly contentious field, multiple notices of opposition were filed in the opposition window. The opponents filed as part of their arguments that the patent was not entitled to claim priority from several of its 12 priority documents. Importantly, this includes the two key provisional applications with the earliest priority dates. Maintaining these priority dates was key to The Broad Institute’s patent strength, as a number of novelty destroying documents were published shortly after these priority dates, and several patents from competitors in the field were also filed around the same time.

Invalid Priority Claim?

As pointed out by the opponents, the applicants on the two priority documents (2x US provisional filings) in question were not identical to the applicants on the PCT application from which EP 2771468 was derived, and thus the priority claim was invalid.  Specifically, Luciano Marraffini (an inventor and applicant on both priority documents) did not transfer his right of priority derived from the two US provisional filings to any of the PCT application applicants before the filing date. Marraffini did assign his rights at some point, but to his employer Rockefeller University, and neither he nor Rockefeller University were named as applicants for the PCT application. In fact, The Broad Institute and Rockefeller University had at the time been locked in a patent dispute over whether Luciano Marraffini should be included as an inventor on the patent. Some opponents pointed out this as evidence that the priority right was never assigned.

In their response to the opponents’ submissions and the EPO Opposition Division’s initial ruling that “neither the requirement of the applicant’s identity nor the proof of a valid success in title [had] been fulfilled“, Broad Institute primarily argued that national law should be used to determine if the right to priority was correctly assigned at the time of filing the PCT application. They submitted that the EPO case law cited by the opponents is not in line with the principles of the right to claim priority of the Paris Convention, and argued that the legal requirements should be assessed under US law, as the inventors and applicants were US based and the priority documents were US provisional applications.

Under US law to be named as an inventor on a patent application, or to claim priority to an invention, the inventor must have contributed to the invention in question. They submitted that Marraffini was not entitled to the right to the specific invention to which the PCT application filed for, and that is why he wasn’t named as an applicant. His contribution to the priority document, which contained multiple inventions, was to a different invention in the priority document, and was the subject of other PCT application(s) they submitted. To support their position, The Broad Institute obtained declarations from high profile figures such as Lord Hoffman.


The Decision

In the Opposition hearing of January 2018, the Opposition Division ruled that the opponents’ arguments were persuasive, and that the priority claims were invalid. They found that no evidence had been filed regarding the transfer of the priority rights of Marraffini in relation to the key priority documents before the date of filing the PCT application. They further stated that in order to decide if Marraffini should have been entitled to be named as an applicant on the PCT application, i.e. deciding on his contribution to the invention would be equal to assessing entitlement to the EP application, for which the EPO is not competent to do, and thus does not do. Following the interpretation of the Paris Convention and the EPC in established EPO practice, they would not rule on entitlement, thus they declared that the application could not validly keep several of its key priority dates.

The opposition division ruled (in line with established case law) that the EPO has the power to rule on priority and found that the priority rights of the two key priority applications was not validly claimed. This resulted in the key priority claims falling down, the patent becoming open to a number of novelty attacks and thus being revoked.


The Future

Unsurprisingly, given the value of the technologies at stake, The Broad Institute filed a notice of appeal against the decision within days of the hearing. It seems their appeal argument will focus on the fact that the law is inconsistent, and submit that “the EPO will, on appeal, harmonize the EPO procedures to be consistent with international treaties and compatible with the fundamental principles of the Paris Convention”. They will perhaps seek to have some form of partial priority, with the PCT application only claiming priority to part of the priority documents in question. The EPC is actually silent on which law should be used to assess the validity of a transfer of priority, so the Board of Appeal will have to determine the applicable law for this issue.

There are many different laws being discussed here (the EPC and EPO case law, the Paris Convention and US national law), and without discussing the validity of the various arguments or digging too deep into the minute detail of these, it will be very interesting to see the result of the appeal.


Conclusion and Best Practice Notes

The decision of the board of appeal should help clarify matters in Europe. As outlined in EPO Board decision 1201/14, “the EPC lays down no formal requirements for the conclusion of such a transfer. Nor is this issue regulated in the Paris Convention…”. There is a debate to be had as to which national law applies to the transfer of priority, and even the way in which rights can be transferred is up questionable as there are no formal assignment requirements laid out in the EPC.

As this interesting recent case demonstrates, it is key for applicants and their representatives to understand and track priority rights when filing any applications claiming priority from an earlier application. That being said, the EPC case law is clear and the right should be sorted out (and assigned where necessary) before filing of any priority claiming application.

Where the applicants of the first application and a subsequent application (e.g. a PCT application) are not identical, it has to be proven that the right of priority derived from the first application has been transferred by the applicant of the first application to its successor in title, in accordance with specific formal requirements. To save any issues, where there are problems likely to arise, different filing strategies can be considered, e.g. filing an application claiming priority with the same applicants as the original filing, and then assigning the application to the new owner afterwards.

TLIP always carefully investigates such issues when filing applications, and has much experience in handling filings claiming priority, in multiple different jurisdictions. If you would like any advice on such matters, please don’t hesitate to get in touch.