In 1962, the American Law Institute published its Model Penal Code, which includes an insanity test later adopted by many states. The second paragraph of the test excludes people with certain psychiatric conditions manifested by repeated criminal or antisocial conduct from using them as a basis for an insanity defense. Oregon adopted this test in 1971. Since then, its legislature and courts have added to the conditions excluded in the second paragraph. In this article, we look at how recent Oregon appellate court decisions have culminated in a narrower and less contentious notion of which psychiatric diagnoses serve as a basis for an insanity defense. Then we discuss Oregon's expansion of the second paragraph of the American Law Institute Insanity Test in a national context.