In Williamson v. Citrix Online, LLC, No. 2013-1130, the Federal Circuit recently overruled earlier precedent and eliminated the “strong” presumption that a functional claim limitation lacking “means” language does not invoke 35 U.S.C. § 112, para. 6 (post-AIA § 112(f)). This is a significant change in the law that should be taken into account in patent prosecution and enforcement.

The New Standard -

Previously, the standard set forth by the court in Lighting World1 was that “the presumption flowing from the absence of the term ‘means’ is a strong one that is not readily overcome.” Later, in Flo Healthcare Solutions, the court went slightly further, declining to apply “[the] provision without a showing that the limitation essentially is devoid of anything that can be construed as structure.”2 But the en banc court in Williamson abandoned both positions, and expressed concern with what it sees as “a proliferation of functional claiming untethered to [§ 112, ¶ 6] and free of the strictures set forth in the statute.