The Federal Circuit used a video game patent-infringement case Wednesday to clarify that expert witnesses must rely on the exact definitions agreed to by the parties for terms used in patent claims, saying experts are not free to adopt different definitions—even if they don’t conflict with the original construction.
In a precedential opinion Wednesday, a three-judge panel affirmed a Washington district court that struck portions of patent owner Treehouse Avatar LLC’s expert testimony and cleared video game company Valve Corp. of infringement allegations.
“When the court has adopted a construction that the parties requested and agreed upon, any expert theory …
