P was injured in an auto accident on October 1, 1943. P sued in diversity on September 4, 1945, by filing the complaint with the court. Service was had on December 28, 1945. Merchants (D) moved for summary judgment based on the state two-year statute of limitations applicable to such tort claims. D claimed that the filing of the complaint tolled the statute. Kansas law provides for the commencement of the action on the date of service. Under Kansas law, the statute of limitations was not tolled until service of process. Federal law tolled the statute of limitations on the date of the filing. The District Court denied D’s motion. P got the verdict by trial and D appealed. The Court of Appeals reversed. The Supreme Court granted certiorari.