Invention Analysis and Claiming:
Claims With Functional Language¹

By Ronald Slusky

Certain kinds of claims are said to be “functional.” But what that actually means depends on who you ask. Judge Giles Rich once observed that “[f]ew words in patent law have acquired more diverse meanings than the word ‘functional.’”²

So if we are going to make sense out of this topic we need to first explore its terminology.

We begin with what it means for a claim to have “functional language” or, equivalently, to have “functional recitation(s).” Happily, we don’t need a strict definition; in the end, we will be analyzing our claims based on what they actually say, rather than whether any particular recitation does or does not meet anyone’s idea of what it means for language to be “functional.” Indeed, the next several months’ columns devoted to this topic aim to impart an understanding of first principles that will enable the practitioner to readily assess whether any given claim with functional language is patentable or not, and to be able to easily explain why.

“FUNCTIONAL LANGUAGE” BUT NOT “FUNCTIONAL CLAIM”

A useful working definition of functional claim language is any recitation that is other than a purely physical characterization of a tangible object. Functional language thus encompasses, inter alia, statements of function,...