Co-Counsel’s Malpractice Win Sinks Parallel Suit

A company can’t sue a Manhattan firm that represented it in a business dispute after losing—and settling before appeal—a parallel malpractice action in New Mexico against a firm that served as co-counsel in the underlying litigation, an intermediate New York appeals court held Jan. 11.

The panel tackled a question that few courts have addressed: whether an ex-client who accuses two firms of botching its case can bring a malpractice action against one of the firms despite having lost a malpractice suit in another jurisdiction against the other firm.

The plaintiff in this case, Guidance Endodontics LLC, initially sued both ...