For claims against one defendant to relate back to claims asserted against another, a plaintiff must demonstrate: (1) that both claims arose out of the same conduct, transaction, or occurrence; (2) that the new party is united in interest with the original defendant such that it may be charged with such notice of the institution of the action that it will not be prejudiced in maintaining its defense on the merits; and (3) that the new party knew or should have known that, but for the plaintiff's mistake as to the identity of the proper parties, the action would have been brought against the new defendant as well. The linchpin of the relation-back doctrine is whether the new defendant had notice within the applicable limitations period.
Louis v. Sood, NY Slip Op 04494 (2d Dep't July 22, 2026)
