How does the preamble affect Jepson claims in patent applications?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

The preamble plays a crucial role in Jepson claims, a specific claim format used in patent applications. According to MPEP 2111.02, in Jepson claims, the preamble is always regarded as a limitation of the claim.

The MPEP states: “In Jepson claims, the preamble is considered to positively and clearly include all the elements or steps recited therein as a part of the claimed combination.“

Key aspects of preambles in Jepson claims:

• The preamble describes elements or steps of the claimed invention that are considered prior art.
• It is followed by the phrase “wherein the improvement comprises” or similar language.
• Everything in the preamble is considered a limitation and part of the claimed invention.
• The body of the claim then describes the improvement or novel aspects of the invention.

For example, a Jepson claim might start: “In a computer system comprising a processor and memory, wherein the improvement comprises…” Here, the computer system with a processor and memory is considered prior art and a limitation of the claim. The improvement described after this preamble is the novel aspect of the invention.