Federal and State courts have generally applied one of four tests to determine sanity: the M'Naghten test, the irresistible impulse test, the Durham test, and the American Law Institute test. The major problem with all the insanity tests has been determining proper limitations to be placed upon expert testimony involved in applying the tests. In all the tests, the only limitations imposed on the admissibility of evidence were made by psychiatrists. Furthermore, psychiatrists limit their testimony to conclusions and fail to supply underlying evidence for the conclusions. However, the decision to exempt a mentally disordered person from punishment requires a moral judgment. Such judgments are usually based on community standards. Ultimate determinations on sanity and the use of expert testimony should therefore be made by the community through legislatures. Specific attention is directed to the development of the insanity defense in the District of Columbia courts. A total of 121 case notes are provided.