415 F.3d 1303 (Fed. Cir. 2005) Cited 5,839 times 167 Legal Analyses
Holding that "because extrinsic evidence can help educate the court regarding the field of the invention and can help the court determine what a person of ordinary skill in the art would understand claim terms to mean, it is permissible for the district court in its sound discretion to admit and use such evidence"