Whether a patent claim is indefinite under § 112, ¶ 2, if conflicting positions about a claim term arise during the patent prosecution process, even if uncontradicted expert testimony established that the term has a reasonably certain meaning to those skilled in the art

QUESTION PRESENTED The Patent Act provides that a patent “specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.” 35 U.S.C. § 112, § 2 (2006). A patent claim that is insufficiently “definite” under this provision is invalid. In Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898 (2014), this Court made clear that “[d]efiniteness is measured from the viewpoint of a person skilled in [the] art at the time the patent was filed.” Id. at 908 (alterations in original). Although the only evidence in this case on how those skilled in the art would understand two disputed claim terms came from the patent owner’s expert, the Federal Circuit treated the issue as a purely legal one and concluded that two supposedly inconsistent positions found in the prosecution history rendered the disputed terms indefinite, rendering the claims invalid. The question presented is: Whether a patent claim is indefinite under § 112, 4] 2, if conflicting positions about a claim term arise during the patent prosecution process, even if uncontradicted expert testimony established that the term has a reasonably certain meaning to those skilled in the art. (i)