In State v. Meiser, 506 P.3d 402 (Or. 2022), the Supreme Court of Oregon considered whether a defendant entering an insanity plea is required by state law to prove that his asserted insanity was caused exclusively by a qualifying mental disorder and not in any way by a co-occurring personality disorder. Given the high rate of comorbid personality disorders, the state supreme court’s ruling in Meiser has the potential to affect many defendants in Oregon considering a plea of guilty except for insanity. In the absence of a known limit, the forensic mental health evaluator can aid the trier of fact in parsing the relative contributions of qualifying and nonqualifying disorders to the defendant’s mental state at the time of the crime.