Unique Concepts, Inc. v. Brown
United States Court of Appeals for the Federal Circuit
939 F.2d 1558 (1991)
Unique's (plaintiff) patent for wall-hanging border assemblies claimed "linear border pieces and right angle corner border pieces," with drawings and specification depicting only preformed corner pieces, while a since-cancelled dependent claim had specifically covered mitered linear pieces fitted together as corners; when Brown (defendant) made products using mitered linear pieces assembled into corners, Unique sued for infringement, but the district court found the patent language covered only preformed corner pieces, finding no infringement.
Whether, when patent claim language is clear, a court can consider extrinsic evidence in a way that would render the express claim limitations meaningless.