Can an arbitration clause adopted today require arbitration of a dispute that arose before the clause existed? In Deshmukh v. Kasowitz Benson Torres LLP, 2026 N.Y. Slip Op. 06550 (1st Dept. Nov. 10, 2026), the Appellate Division, First Department confronted that question in an unusual circumstance involving a law firm partner who left the firm, later returned, and became subject to a new partnership agreement containing an arbitration provision.