In an action for negligence, a plaintiff may make a claim for mental injury resulting from the defendant’s conduct. For years, the common law has struggled with the question of whether the plaintiff needs to tender expert evidence to prove that she has suffered a recognized mental illness. A 2017 decision of the Supreme Court of Canada, Saadati v. Moorehead, 2017 SCC 28, puts this question to rest and reflects an important evolution regarding the legal treatment and understanding of mental injury.