The criminal justice system regularly relies on psychiatric evidence to guide policy decisions related to issues of a defendant’s competency to stand trial, culpability, and sentencing. Using psychiatric and psychological evidence is meant to ensure fair outcomes for defendants who may not be morally blameworthy for their actions. Defendants with recognized behavioral, psychological, or biological dysfunctions that limit their capacity to distinguish right from wrong are arguably less responsible for their crimes, and their sentences should reflect this diminished culpability. However, as the psychiatric community continues to study known disorders, the implications of a particular diagnosis related to an individual’s underlying behavioral characteristics similarly evolves. In State v. Amaral, the Arizona Supreme Court considered whether advances in juvenile psychology and neurology over a twenty-year period constituted a colorable claim of newly discovered evidence in a post-conviction relief proceeding. This Note identifies a potential misinterpretation of the holding and examines why this interpretation is flawed, particularly under the contemporary DSM-5. It then identifies the proper inquiry of whether new research or evidence of a mental disorder constitutes newly discovered evidence, thereby showing how Amaral aligns with policy goals.