NGRI

Not Guilty by Reason of Insanity (NGRI) is a legal defense used in some criminal cases. It asserts that the defendant was suffering from a mental disease or defect at the time of the offense and therefore could not be held legally responsible for the crime. If successful, the result is typically an acquittal on the charged offense, rather than a conviction, though the individual may be subject to commitment for treatment.

Standards for NGRI vary by jurisdiction. The most enduring test is the M’Naghten Rule, which asks whether the defendant knew the nature and quality of the act or knew that it was wrong. Other tests include the Irresistible Impulse standard, which considers whether mental illness prevented self-control, and the Model Penal Code standard, which focuses on a lack of substantial capacity to appreciate the wrongfulness of the conduct or to conform it to the law. Some jurisdictions used or still use the Durham rule (the act caused by mental illness), though it is less common today. Burden of proof and the factual thresholds differ by place, often requiring proof by a preponderance or clear and convincing evidence.

Post-verdict consequences commonly involve civil commitment rather than punishment. Individuals found not guilty by reason of insanity may be held in secure psychiatric facilities for treatment, with periodic reviews to determine if they remain dangerous or competent for release.

Criticism of the NGRI defense centers on concerns about public safety, diagnostic reliability, and stigma. Some jurisdictions have reformed systems by adopting alternatives such as “guilty but mentally ill” or other standards that balance treatment needs with accountability.