By Steve Benmor ( January 14, 2026, 1:40 PM EST) -- In Ontario, claims that a lawyer made an error in handling a client’s case are tested under the law of professional negligence. These claims are often referred to as “lawyer negligence” or “professional malpractice.” While clients may feel strongly that their lawyer’s conduct caused them harm, Ontario courts apply a structured and demanding legal test before holding a lawyer liable....