Two recent decisions from the nation’s patent appeals court offer valuable lessons in crafting language in patent applications, practitioners say.

The U.S. Court of Appeals for the Federal Circuit handed a win to AT&T Mobility LLC and Ericsson Inc. Aug. 12 after analyzing language in a communications patent. The appeals court nixed a win for Toro Co. in another Aug. 12 decision after finding a U.S. Patent and Trademark Office administrative tribunal erred in analyzing a patent’s claims.

The decisions are “great examples of cases at opposite ends of the spectrum” in illustrating why practitioners “have to be careful in...