Who has priority? (or, Getting your priorities straight)

This article was included in our Winter 2009/10 edition of Inside IP.

A recent decision by the UK Patents Court emphasises the importance of ensuring that an applicant has acquired the right to claim priority before the application claiming priority is filed.  In Edwards Lifesciences v Cook Biotech, the patent in question was found to be invalid by being obvious.  The patent claimed priority from an earlier application and the fact that the priority claim was found invalid played an important role in establishing that it was obvious since one of the cited prior art documents was published between the claimed priority date and the filing date of the patent.

As factual background, in early 2000, a US patent application was filed naming as applicants three inventors, only one of whom was an employee of Cook Biotech (“Cook”).  Within the priority year, a PCT application was filed in the name of Cook.  The other two inventors’ interests in the invention were assigned to Cook, but only in September 2002, 21 months after the PCT application was filed.  The PCT application resulted in the grant of an EP patent and the patent was validated in the UK.

The Claimant, Edwards Lifesciences, argued that the claim to priority of the patent was invalid since the right to priority may only be enjoyed by the person who filed the priority application or his successor in title and at the PCT filing date the right to priority was not Cook’s alone but belonged to Cook jointly with the other two inventors.  Cook, as Defendant, argued that the claim to priority was a good one because the interests of the other two inventors were assigned before the date of grant and, in any event, Cook always owned one of the inventors’ interests.

The case comes down to the interpretation of Article 4 of the Paris Convention, on which the relevant provisions of the PCT, the EPC and the Patent Act 1977 are based.  Article 4A(1) states: “Any person who has duly filed an application for a patent … or his successor in title, shall enjoy, for the purpose of filing in other countries, a right of priority …”.  Mr Justice Kitchin argued that the law was therefore clear: “[a] person who files a patent application for an invention is afforded the privilege of claiming priority only if he is the successor in title to the person who filed that earlier application.  If he is neither the person who filed the earlier application nor his successor in title then he is denied the privilege.

Moreover, his position is not improved if he subsequently acquires title to the invention.  It remains the case that he was not entitled to the privilege when he filed the later application and made his claim”.  Since the assignments to Cook had been executed after the filing date of the PCT application, their first argument failed.  The argument that Cook always owned one of the inventors’ interests in the invention and that was sufficient was quickly dismissed by Mr Justice Kitchin on the basis that the US application was filed in the names of three inventors and not by the employee of Cook alone and therefore Cook was not “a person” who had “duly filed an application for a patent” within the meaning of Article 4A(1) of the Paris Convention.

The Patents Court therefore held that the claim to priority was invalid and that the document published between the priority date and the filing date was prior art.  The Judge further pointed out that the approach used when considering the issue of priority was consistent with the position of the Board of Appeal of the EPO in cases J 0019/87, T0062/05 and T 0788/05.

The decision emphasises the importance of getting all necessary assignments in place before the end of the priority year.  Additionally, although in most cases the validity of a priority claim is disputed on the grounds that the subject matter of the later application was not actually disclosed in the priority application and this should of course be considered when assessing the validity of a priority claim, the technical question as to whether the applicant(s) of the later application are entitled to claim priority also is important.  The validity of a priority claim can be particularly relevant when considering the relevance of “novelty only” prior art, cited under Article 2(3) Patents Act 1977 and under Article 54(3) EPC, which is published later but has an earlier priority date than the patent in question.  If the applicant of the later application is different to the applicant of the priority application it can be worth investigating how and when, if at all, the applicant of the later application acquired the interest in the invention, and particularly acquired the right to claim priority.  This is particularly relevant when the priority application is a US application since US applications must initially name the inventors as applicants whereas later applications, outside the US, are usually filed naming a company as applicant.

Olivia Johansson 05 Nov 2009

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