User:Doctor Whom/Sandbox/Doctrine of claim differentiation

In United States patent law, the doctrine of claim differentiation is a doctrine used to interpret patent claims. The doctrine holds that "different words or phrases used in separate claims are presumed to indicate that the claims have different meanings and scope." It is often used to raise a presumption that an independent claim is broader than a claim dependent therefrom, to avoid a narrow interpretation of the independent claim to say otherwise.

Under 35 U.S.C. § 112(d) and its predecessor statutes, "a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed."

The presumption is typically rebutted by showing that a claim, when read in light of the specification and the prosecution history, necessarily includes the limitation that it is argued not to have.