Chapter §5.05 Best Mode Compliance and Foreign Priority Claims

• Jurisdiction: United States

§5.05 Best Mode Compliance and Foreign Priority Claims

Prior to enactment of the AIA, the absence of a best mode requirement in many foreign patent systems coupled with the presence of the requirement in the U.S. system was thought to potentially disadvantage foreign nationals seeking U.S. patent protection.³⁰ The disadvantage could occur in the following manner. As discussed in Chapter 25 ("International Patenting Issues"), in Volume II of this treatise, a foreign national might have needed to rely on the earlier filing date of her home country ("foreign priority") application to avoid prior art cited by a USPTO examiner against her later-filed U.S. application.³¹ To do this she would have claimed for her U.S. application the benefit of her earlier foreign filing date in accordance with 35 U.S.C. §119(a), the domestic implementation of the Paris Convention's right of priority.³² If her later-filed U.S. application was to be entitled to the benefit of her earlier-filed foreign application's filing date under §119(a), the foreign-filed priority application would have needed to satisfy the requirements of 35 U.S.C. §112, ¶1, as of the earlier foreign filing date on which the applicant was relying.³³

Although the courts have not frequently dealt with the issue, it was generally believed before enactment of the AIA that satisfying the requirements of 35 U.S.C. §112, ¶1 in a manner that would support a foreign priority claim under 35 U.S.C. §119(a) mandated satisfaction of the best mode requirement, because best mode is one of the three disclosure requirements set forth in 35 U.S.C. §112, ¶1. In other words, the consensus view was that the priority (foreign) application had to include a description of the best mode for carrying out the invention claimed in the corresponding later-filed U.S. application.³⁴

If the foreign priority application was first filed in a foreign country that did not have a best mode requirement (and many foreign countries do not³⁵), the foreign priority application might not adequately disclose the best mode of carrying out the invention claimed in the corresponding laterfiled U.S. application. In such a case, it was thought that the applicant would not be able to claim priority back to her home country (foreign priority) filing date. Instead, the filing date of her U.S. application would be the later-in-time date of its actual filing in the USPTO, and the applicant would not be able to avoid the cited prior art by claiming the benefit of her foreign priority date under 35 U.S.C. §119(a).

Enactment of the AIA very likely changed this result, although the issue is still not...