Chapter §5.01 2011 Legislative Scale-Back of the Best Mode Requirement

• Jurisdiction: United States

§5.01 2011 Legislative Scale-Back of the Best Mode Requirement

The best mode requirement of 35 U.S.C. §112, ¶1, obliges an inventor to disclose the best way known to her on her patent application filing date of "carrying out [the] invention."¹ The requirement goes beyond the objective standard of enablement² to mandate disclosure of what the inventor believes to be the best mode, not just a mode, of practicing her invention. Because the best mode is, in part, a subjective inquiry with the potential for significant litigation expenditures to discern what was in the inventor's mind at a particular (sometimes long-past) date, some policymakers objected to the continued presence of a best mode disclosure requirement in U.S. patent law.

In response to these concerns, patent reform legislation enacted in the fall of 2011 significantly cabined the scope of the best mode disclosure requirement.³ The Leahy-Smith America Invents Act of 2011 (AIA) prohibits asserting best mode non-compliance as grounds for challenging an issued patent's validity or enforceability in either federal court litigation or as part of a post-grant opposition proceeding in the U.S. Patent and Trademark Office (USPTO).⁴ This important change took effect on the AIA's enactment date of September 16, 2011, and applies "to proceedings commenced on or after that date."⁵

Although best mode non-compliance is no longer a basis for challenging the validity of an issued patent, pending patent applications remain subject to compliance with the best mode requirement. The first paragraph of 35 U.S.C. §112 was not amended to remove the best mode requirement; the best mode disclosure obligation remains one of three disclosure requirements for patent applications.⁶ Despite the AIA's enactment, the USPTO retains the ability to reject a pending patent application for failure to identify the best mode.

Historically, however, "such rejections are reported to be rare."⁷ Because of the subjective, inventor-centric nature of the best mode disclosure requirement, as well as the USPTO's limited fact-finding resources, a patent applicant's failure to disclose the best mode would be difficult for the agency to discern.

Despite the elimination of best mode non-compliance as a basis for contending that an issued patent is invalid, understanding the best mode requirement remains vital. Importantly, the best mode disclosure obligation continues as a statutory requirement for patent applications, as it has since 1870.⁸...