When does an examiner consider the merits of a foreign priority claim?

An examiner considers the merits of a foreign priority claim in the following situations:

• When a reference is found with an effective date between the foreign filing date and the U.S. filing date
• When determining if a reference’s prior art date falls within the grace period for the application under examination
• When an interference situation is under consideration

The MPEP states: “The subject matter of the application is not examined to determine whether the applicant is actually entitled to the benefit of the foreign filing date on the basis of the disclosure thereof unless such determination is required for patentability reasons. For example, the examiner considers the merits of an applicant’s claim of priority when a reference is found with an effective date between the date of the foreign filing and the date of filing in the United States, when determining whether a reference’s prior art date is within the grace period for the application under examination, and when an interference situation is under consideration.” (MPEP 216)