How does the preamble affect claim interpretation in Jepson claims?

Jepson claims have a unique structure that affects how the preamble is interpreted. According to MPEP 2111.02, “In Jepson claims, the preamble is considered to positively recite the structure or steps that are the conventional or known aspects of the invention.” This means that in Jepson claims, the preamble is automatically treated as a limitation and is considered part of the claimed invention.

The structure of a Jepson claim typically includes:

• A preamble describing the conventional or known elements
• A transitional phrase like “wherein the improvement comprises”
• A body reciting the new or improved elements

Because the preamble in a Jepson claim explicitly states what is known in the prior art, it serves as an implied admission that those elements are not the applicant’s invention. This can affect both patentability determinations and infringement analyses.

To learn more:

• Jepson claims
• preamble interpretation
• claim structure
• prior art admission