A Houston-based commercial real estate law firm is in a legal fist fight with a former client that manages apartment communities across the country—a client it represented for seven years.

Brian P. Cweren and The Cweren Law Firm just lost an appeal to the First District Court of Appeals, which affirmed a Harris County 55th District Court ruling that denied the law firm's motion to dismiss a suit Cweren claims is in retaliation to a billing collections lawsuit in another court.