Abolition of the insanity defense violates due process.

This article, which is based on and expands on an amicus brief the authors submitted to the United States Supreme Court, first provides the moral argument in favor of the insanity defense. It considers and rejects the most important moral counterargument and suggests that jurisdictions have considerable leeway in deciding what test best meets their legal and moral policies. The article then discusses why the two primary alternatives to the insanity defense, the negation of mens rea and considering mental disorder at sentencing, are insufficient to achieve the goal of responding justly to severely mentally disordered offenders. The last section considers and rejects standard practical arguments in favor of abolishing the insanity defense.