Review of the changes in patent filing strategies for the pharmaceuticals and biotech industry

Review of the changes in patent filing strategies for the pharmaceuticals and biotech industry in Europe in light of the recent opinion G2/98¹ from the European Patent Office in respect of the requirement for claiming priority for the same invention.

Author: Stephanie Michiels, European Patent Attorney

Introduction
In any patent filing strategy, the benefits associated with filing as quickly as possible to secure the earliest possible date must be carefully balanced with the requirement to generate sufficient technical information to support the patent application. The right of priority has the effect that the date of an earlier application (generally a national application) counts as the date of filing of later applications (usually an International application) filed within a year from the date of filing of the first application. Although disclosures of the invention during the priority year actually occur before the filing date of the later application, they can be overcome by relying on the priority date. In highly competitive and evolutionary areas in particular, it is thus critical to secure a valid priority date for the invention eventually claimed and upon which it can be relied. The validity of the priority right depends on both formal and substantive requirements, including the requirement for claiming in the later application the 'same invention' as that disclosed in the earlier application. The question as to what extent a later filed European patent application can claim priority from an earlier application has recently been reconsidered by the European Patent Office¹ with a definitive ruling from the Enlarged Board of Appeal.

This article examines the implications that this decision will have for those filing patent applications in the Pharmaceutical and Biotechnology Industries.

Background: The Priority System
Typically, any patent application that is filed today in the pharmaceutical and biotechnology sectors claims at least one earlier priority date from a domestically filed national patent application. The facility to do this, of course, arises from the Paris Convention² which permits an inventor (or successor in title) to enjoy a priority period of 12 months from the date of first filing within which corresponding applications can be filed in any other member state which is party to the convention. The later filed applications can then rely upon the earlier filed application to overcome any disclosure of the invention during the priority year, thus permitting the inventor to publish the invention in the scientific literature, without invalidating the later filed applications that relate to the same invention. In Europe, provisions similar to those of the Paris Convention have been incorporated into the European Patent Convention³ (EPC) to allow for a claim to priority to be made from an earlier national filing. In particular, Article 87 EPC provides that the later filed European application must be filed during the period of 12 months from the date of filing of the earlier application, and in respect of the same invention as the one disclosed in the earlier application.

While an applicant can freely indicate a priority claim when filing the subsequent European application, generally the question of the validity of the priority claim will only be addressed during substantive examination of the application and only then if prior art is brought to light which may prejudice the patentability of the claims, should the claim to priority be declared invalid. A valid priority right is required when it is necessary to overcome such a prejudicial disclosure which may have been published during the priority year or to overcome the novelty destroying disclosure of a conflicting European application under Article 54(3) EPC⁴.

In the above circumstances, therefore, establishing whether a priority application is filed in respect of the same invention will determine whether the claim to priority is valid or not. This can be rather uncertain in particular cases where the scope of the claims has been amended during the priority year as is often the case in evolutionary technologies. The question as to whether the same invention is described in an earlier priority document was examined in a number of cases by the EPO but two divergent lines developed.

The EPO case law in respect of the 'same invention'
According to EPO practice, the right to claim the priority of a previous first application is determined by and limited to the extent to which the subject matter claimed in the later application has been at least implicitly disclosed in the first application. In an early decision, T81/87 (Preprorennin/COLLABORATIVE)⁵, which established a stricter narrower approach to priority determination, it was emphasised that when it comes to priority, the disclosure of all the essential elements must be expressed or 'be directly and unambiguously implied by the text as filed'.

Thus according to this strict approach, the validity of the claim to priority depends on the explicit and implicit disclosure of that subject matter in the earlier application ('Novelty Approach'). Priority will only therefore be accorded to subject-matter disclosed in the application which is directly and unambiguously derivable from the priority document, either explicitly or implicitly.

The second line of case law developed from T73/88 (Snackfood/HOWARD)⁶, known as the Snackfood decision. In this Decision, the Technical Board of Appeal adopted a much broader approach and held that priority could be acknowledged for a feature not necessarily disclosed in the priority application as long as that feature is not related to the function and effect of the invention ('Essentiality Approach'). Thus, according to this test, priority for a new feature can be claimed if it is not essential to the way the invention works. At issue in this case was the entitlement to priority of a claim to a snackfood product, including in the pre-characterising portion the feature that the snack food contained 'at least 5% by weight of oil and fat' and which was not mentioned in the priority document.

Although the Board considered that the feature added to the claim was 'clearly an essential technical feature of the claims in that it has the effect of limiting the extent of the protection conferred by the patent', the Board also emphasised that the feature 'is not necessarily an essential feature for the purpose of determining priority" (point 2.3 of the Reasons for the Decision). In the Board's view, 'it is clear from the European patent that the additional technical feature ... has nothing to do with the essential character and nature of the invention as such ... The presence of the additional feature does not therefore change the character and nature of the claimed invention as such, in comparison with what is disclosed in the priority document' (point 2.4 of the Reasons for the Decision).

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