Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co.

Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co. was a legal case that addressed patent law, specifically about whether a patentHolder can claim infringement if a competitor’s product slightly modifies a patented feature. The court ruled that if a competitor’s change is a permissible "equivalent"—meaning it performs a similar function in a similar way—it may not infringe the patent, especially if the patent owner previously narrowed their patent claims or failed to include certain details. This case clarified how courts interpret patent infringement when products are similar but not identical, emphasizing the importance of specific claim language and patent scope.