Doctrine of Claim Differentiation Law and Legal Definition

Doctrine of Claim Differentiation is a canon of construction used in Patents law. The doctrine in its broadest reading provides that no two claims in the same patent should be interpreted to cover the same thing. It is presumed that each claim in a patent is different in scope and meaning from all other claims. The presumption is strongest when a different interpretation would be the only way to make a dependent claim more limiting than the independent claim it refers to.

Application of the doctrine generally results in broader constructions of patent claims, because it is most commonly used to prevent defendants from limiting a broad genus claim to the range of embodiments actually disclosed or more explicitly recited in other claims. However, this doctrine cannot be used by the patentee to broaden claims.

It is improper for courts to read into an independent claim a limitation explicitly set forth in another claim. [Environmental Designs, Ltd. v. Union Oil Co., 713 F.2d 693, 699 (Fed. Cir. 1983)]