While most attorneys have heard of means-plus-function, most have not heard of or given much thought to its sibling, step-plus-function. Both claims arise under the same section of the patent laws, namely 35 U.S.C. § 112, ¶ 6. While means-plus-function limitations are directed to structural limitations and most often appear in apparatus claims, step-plus-function limitations are directed to steps and most often appear in method claims. Means-plus-function limitations generally arise when the patentee chooses to recite a “means for” performing a specified or recited function rather than reciting the structure or material that performs that function. Step-plus-function limitations, on the other hand, potentially arise when a claim drafter chooses to recite a “step for” performing a specified or recited function. This article analyzes the limited but complex jurisprudence surrounding step-plus-function limitations. Finally, the article provides tips for avoiding step-plus-function limitations and proposes that recent decisions may allow courts to step away from Judge Rader’s complicated analysis, so courts may neither have to confront the “difficulty of distinguishing acts from functions” nor engage in a “careful analysis of the limitation in the context of the overall claim and the specification” in order to discern whether a step-plus-function limitation exists.
Paul R. Kitch, Step-Plus-Function: Just What Have We Stepped Into?, 7 J. Marshall Rev. Intell. Prop. L. 117 (2007)