What is double patenting?

Double patenting is a term used in Europe to describe a situation in which an applicant secures (or tries to secure) two separate patents to the same subject matter. It is distinct from the so-called “obviousness type double patenting” encountered in the US – it is only the scope of the claims that is considered, without regard to their teaching. There is no statutory basis prohibiting double patenting between two European patents/applications. Nonetheless, a double patenting objection based on another European patent is presently a reason for refusal by the EPO, although it cannot be used to attack a patent during post-grant proceedings. The guiding principle at the EPO is that an applicant has no “legitimate interest” in grant of a second patent for the “same subject-matter” already claimed in a first. This understanding has developed through case law and practice. However, the application of that principle, and in particular the interpretation of what is the same subject matter has not always been straightforward, or even consistently applied.¹

What questions are being referred?

The referring case () relates to an EP application that contains identical claims to its already granted priority filing. So, the two filings share the same applicant and the same priority date, and the applicant is pursuing the same claims. Crucially, the later filing will expire one year later, so at stake is an extra year of patent term. A previous Board of Appeal decision considered this “legitimate interest”, but this was contradicted in the comments of a later decision. Board of Appeal 3.3.01 now seeks clarification on whether extra patent term alone constitutes legitimate interest (Question 2.2). Interestingly however, the referred questions are broader in scope and offer the EBOA an opportunity to provide clarity more generally on this sometimes ambiguous aspect of European patent law. Question 1 asks, in simple terms, if European patent applications can be refused because of double patenting. A negative answer would significantly change accepted practice at the EPO and could ultimately lead to more applicants keeping their European-filed priority applications and/or pursuing much more aggressive divisional filing strategies. Question 2.1 asks, if refusal on the basis of double patenting objections is permissible, does the assessment vary with the relationship between the applications. Should related applications be treated differently to two applications filed on the same day by the same applicant(s)? Does the nature of the relationship between the applications (i.e. by priority claims or as divisional siblings) matter? The questions therefore relate primarily to the relationship between the applications and the principle of legitimate interest, and clarification from the EBOA on these points will be welcome. However, clarification on what constitutes identical subject matter is also needed. In our experience this is often the deciding factor in whether or not there is a double patenting issue in a case. For example, in (Apo-2 ligand/Genentech) the Board had to consider whether double patenting existed with respect to two different types of medical use claims (the so-called “Swiss” type and the EPC2000 type). Their conclusion was “no” as the claim categories were different, but where the claims of the two applications are in the same category but non-identical remains a grey area. There have also been comments in EBOA cases and that double patenting objections are only proper when two applications claim the same invention using identical wording. We will watch this case with interest to see if the EBOA takes Question 1 as an invitation to consider the issue of the “same subject matter” in detail and settle the issue once and for all.

¹ epi Information 3/2011, pp. 100-102 (Bremi and Harrison)