With the changes to the U.S. Patent Act through implementation of the America Invents Act (AIA) on March 16, 2013, all World Trade Organization member countries now follow a first to file system. Under this system, the first inventor to file an application with a patent office obtains a priority date recognized by any patent office that is signatory to the Paris Convention. Even though a unified approach appears to be in place, there are several significant variations in the implementation of the first to file system that need to be considered in any patent filing strategy. Below is a review of several filing strategies that highlight some of the issues.

Grace period

In the first scenario, an enabling abstract is published in advance of a conference, and before a patent application is filed. In several countries a grace period is available for disclosures made directly or indirectly by the inventor, for example 12 months in Canada, Brazil, Australia, Mexico, U.S. and 6 months in Japan, Korea, Russia, Eurasia. If the patent application is filed within the grace period, the inventor-derived publication will not be considered prior art.

Europe does not offer a grace period and the published abstract will be considered prior art against a subsequently filed patent application. This is in contrast to the situation in the U.S., where the published abstract may be beneficial for an application filed after the publication date. The AIA provides a unique variation on the grace period exemption[1] in that a disclosure made by the inventor before the filing date of the inventor’s application may act as a shield against a subsequent publication made by another person before the filing date. In effect, the U.S. has created a “first to disclose” system. While Canada provides a grace period for disclosures made directly or indirectly by the inventor, unlike the U.S., a non-inventor derived publication published in advance of the filing of a patent application will always be considered prior art.

Double patenting

In a different scenario, a company wishing to maximize their patent thicket may file multiple PCT patent applications on the same day; each application being related and having the same priority date but different claims and possibly, with corresponding different specifications in support of these claims. For example, one application may be directed to use of a compound A to treat disease X, whereas a second application may be directed to use of the compound A to treat related disease Y or the use of related compound B to treat disease X. If the PCT applications enter regional and national phases in Europe, U.S.. and Canada, the simultaneously-filed applications are not citable against each other for anticipation or obviousness in any of these countries. However, examination of the PCT applications may take a different path due to double patenting considerations.

Whilst the European Patent Office (EPO), the Canadian Intellectual Property Office (CIPO) and the United States Patent and Trademark Office (USPTO) do not allow two simultaneously-filed applications with identical claims to issue to the same applicant, consideration of non-identical but overlapping claims differs in each jurisdiction.

In Europe, if the claims merely partially overlap, there will be no issue (EPO Guidelines for Examination; Part G - Chapter IV-5.4). The USPTO will raise a nonstatutory obviousness-type double patenting rejection when the claims are not patentably distinct from each. This rejection can, however, be easily overcome by filing a terminal disclaimer at the USPTO linking the two applications together. In Canada, there is no provision for filing a terminal disclaimer and simultaneously-filed applications claiming overlapping subject matter are citable against each other for obviousness type double patenting. CIPO will not allow overlapping claims in separate applications. Furthermore, an issued patent may be invalidated if there is a finding of obviousness type double patenting post grant.

One solution to this problem is to combine all claims from the simultaneously-filed applications in one application, provided there is support for all claims in that application as filed. There are no excess claim fees in Canada and divisional applications may be filed if a unity of invention objection is identified. Any divisional application filed as a result of an examiner’s unity of invention objection is shielded from double patenting issues. If the application disclosure does not support all claims then it will be necessary to limit the claims of each application to patentably distinct subject matter.

Best practice would be to file related inventions in a single application including multiple claims sets. It may be necessary to split the claims out into divisional applications following a unity objection from the examiner; however, such divisional applications cannot be attacked for double patenting.