Understanding Nautilus’s Reasonable-Certainty Standard: Requirements for Linguistic and Physical Definiteness of Patent Claims

Gary M. Fox*

Patent applicants must satisfy a variety of requirements to obtain a patent from the U.S. Patent and Trademark Office (USPTO). The definiteness requirement forces applicants to describe their inventions in unambiguous terms so that other inventors will understand the scope of granted patent rights. Although the statutory provision for the definiteness requirement has been stable for many years, the Supreme Court’s decision in Nautilus v. Biosig Instruments altered the doctrine. The Court abrogated the Federal Circuit’s insoluble-ambiguity standard and replaced it with a new reasonable-certainty standard. Various district courts have applied the new standard in different ways, indicating the need for further clarification. This Note argues that, following the establishment of the reasonable-certainty standard, courts may understand the definiteness requirement under a two-part framework of linguistic and physical definiteness, which are both required for claims to be definite. A claim fails the linguistic-definiteness requirement if it is open to multiple constructions and one construction is not clearly correct. Additionally, a claim fails the physical-definiteness requirement if it uses comparative terms or involves ambiguous spatial relationships not limited to a narrow range.

*J.D. Candidate, May 2018, University of Michigan Law School. I am indebted to Professor W. Nicholson Price II, Thomas Martecchini, Sally Gu, John He, Allison Hight, Z. Zheng, and the Volume 116 Notes Office, who all helped greatly with this Note’s substance, structure, and style. I would also like to thank MNOP and the rest of the MLR crew—particularly AP, DJP, EHK, and my friends in the Volume 116 Articles Office—for their support.

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