How does the principle of claim differentiation affect claim interpretation?

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 principle of claim differentiation is an important tool in claim interpretation. According to the MPEP:

“The presence of a dependent claim that adds a particular limitation raises a presumption that the limitation in question is not found in the independent claim.”

This principle is based on the assumption that each claim in a patent has a different scope. Therefore:

• If a dependent claim includes a specific limitation, it’s presumed that the independent claim it depends from does not include that limitation.
• This presumption can be used to interpret the broader scope of the independent claim.

However, it’s important to note that this is a rebuttable presumption. The MPEP clarifies:

“This presumption is rebuttable if other evidence in the specification or prosecution history clearly indicates that the claims should be interpreted differently.”

Examiners and courts use this principle as one of several tools to understand the intended scope of patent claims.