How does the preamble affect claim interpretation?

The effect of the preamble on claim interpretation is determined on a case-by-case basis. As stated in MPEP 2111.02, “The determination of whether a preamble limits a claim is made on a case-by-case basis in light of the facts in each case; there is no litmus test defining when a preamble limits the scope of a claim.”

Generally, the preamble limits the claim if:

• It recites essential structure or steps
• It’s necessary to give life, meaning, and vitality to the claim
• It’s used to define the scope of the claimed invention

As the Federal Circuit stated in Bell Communications Research, Inc. v. Vitalink Communications Corp., “[A] claim preamble has the import that the claim as a whole suggests for it.”

To learn more:

• preamble
• claim interpretation
• patent claims
• claim construction