Washington
How Durham v. United States applies in Washington: state-specific rules, key cases, and bar exam notes for Criminal Law.
Washington recognizes a modified version of the M'Naghten rule for insanity defenses, which aligns with the principles established in Durham v. United States regarding the treatment of mental illness in criminal liability. This approach emphasizes the necessity of a causal link between mental illness and the criminal act.
In Washington, a defendant can be excused from criminal liability if, at the time of committing the act, they were suffering from a mental disease or defect that prevented them from understanding the nature of their act or distinguishing right from wrong.
The court held that a defendant may establish an insanity defense through expert testimony demonstrating that their mental illness influenced their actions during the commission of the crime.
The court ruled that the jury must consider whether the defendant's mental condition was a substantial factor in their ability to conform their conduct to the law.
This case confirmed that mental illness could provide grounds for an insanity defense if it impacts the defendant's understanding of their actions.
While both Washington and federal law follow similar principles regarding the insanity defense, Washington's application includes a broader interpretation of mental disease and its impact on criminal responsibility compared to the stricter M'Naghten standard traditionally adopted in many federal jurisdictions. Moreover, Washington also provides for a clear distinction in the definitions of 'guilty but mentally ill' which is different from many federal approaches.
The insanity defense under Washington law is a frequently tested area in the Washington Bar Exam, particularly regarding the standards for proving mental illness and its impact on criminal liability.