AT&T Corp. v. Excel Communications, Inc.
United States Court of Appeals for the Federal Circuit
172 F.3d 1352 (1999)
Relevant factsFree
AT&T's (plaintiff) patent covered a message-record process using a mathematical formula and caller information to calculate differential long-distance billing rates; the district court invalidated several claims as unpatentable mathematical formulas falling within the laws-of-nature exception, prompting AT&T's infringement suit against Excel (defendant) to raise the validity question on appeal.
IssueFree
Whether a patent claim for a method or process containing a mathematical formula is valid, patentable subject matter if the claim accomplishes a function the patent laws were intended to protect.
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