In ENZO BIOCHEM INC. v. APPLERA CORP., Appeal No. 2014-1321, the Federal Circuit held that a district court’s factual findings related to extrinsic evidence in a claim construction determination are not given deference on appeal when the claims can be construed based on the intrinsic record alone.

Enzo sued Applera for infringing a patent relating to detecting nucleic acids.  The asserted claims recited a nucleic acid structure including groups A and B.  In the structure, A “represents at least one component of a signaling moiety” and A and B are attached “through a linkage group that does not substantially interfere with . . . formation of the signaling moiety.”  At issue was whether the signaling moiety must have more than one component or whether the signaling moiety may be A alone.  After hearing expert testimony, the district court construed the claim language to mean that A is one or more parts of a signaling moiety, including, in some instances, the whole signaling moiety. The jury found that Applera infringed the asserted claims under this construction. 

On appeal, the Federal Circuit declined to defer to the district court’s fact finding incident to claim construction because the intrinsic record alone could be used to construe the claims.  The Federal Circuit first analyzed the claims’ grammar.  To the Federal Circuit, the phrase “at least one component of” indicated the signaling moiety is a multi-component system. Moreover, because the claims state that A does not interfere with the formation of the signaling moiety , then A by itself cannot be the signaling moiety.  The Federal Circuit next turned to the specification.  The Federal Circuit noted A was described throughout the specification as forming a signaling moiety with other chemicals, never alone. Accordingly, the Federal Circuit concluded the claims do not cover embodiments where A alone is the signaling moiety, and reversed the judgment of infringement.