What is the purpose of functional limitations in patent claims?

The purpose of functional limitations in patent claims is to define an element in terms of what it does rather than what it is. According to MPEP 2173.05(g), “A functional limitation is an attempt to define something by what it does, rather than by what it is (e.g., as evidenced by its specific structure or specific ingredients).”

Functional limitations can be useful when:

• The invention is in a new field
• The invention relates to chemical arts
• The full scope of the invention is difficult to define structurally

However, it’s important to note that functional language must still meet the requirements of clarity and definiteness under 35 U.S.C. 112(b).

To learn more:

• functional limitations
• patent claims
• claim language
• patent drafting