Usually, if a litigant seeks to assert a new claim against a new party in a lawsuit that is already underway, it can only do so if the claim it seeks to assert against that new party is timely. Under certain circumstances, however, the “relation back” doctrine enables the addition of a party mistakenly omitted from an initial pleading—even after the expiration of the statute of limitations. But what constitutes an acceptable mistaken omission?

A recent New York Court of Appeals decision, Nemeth v. K-Tooling, No. 48, 2023 NY Slip Op 05349 (N.Y. Oct. 24, 2023), brings some clarity to that question and moves the relation back doctrine under New York law closer to the tenets of Rule 15(c) of the Federal Rules of Civil Procedure.