Fletcher YoderThe credibility of witness testimony may present a genuine issue of material fact to preclude summary judgment of patent invalidity. It is not sufficient to merely contradict witness testimony. Rather, evidence must be adduced that is contrary to the conclusion put forth by the witness.
In construing claims, it is erroneous to consider intrinsic evidence outside of the claim language (written description, figures, and the prosecution history) if the claim language is clear and its meaning is not contradicted by the written description; the word “substantial” implies “approximate”, and may be used in patent claims to avoid a strict numerical boundary; upon finding non-infringement a District Court may either hear an invalidity counterclaim or dismiss it without prejudice.