A defendant in a criminal case may enter a plea of Not Guilty by Reason of Insanity. After guilt is established by either a trial or a plea, a trial on the issue of sanity will proceed. In the trial, the burden is on the defendant to prove by a preponderance of the evidence that he or she was legally insane at time of the crime. Legal insanity requires that the person, by reason of mental disease or defect was incapable of either:
- Knowing the nature of his or her act
- Understanding the nature of his or her act
- Distinguishing between right and wrong at the time of commission of the crime
If the person is found to be sane by a court or jury, he or she will be sentenced as provided by law. If the person is found to be insane, the person will be confined in a state hospital or placed in the Contra Costa County Conditional Release Program (CONREP). The person may be confined for a length of time equal to the maximum sentence that could have been imposed for their crime. However, the person may be further confined, if the person still has a diagnosed mental disease or disorder and is a substantial danger of physical harm to others. Before confinement beyond the maximum term for the crime may be accomplished, the District Attorney must file a Petition to Extend Commitment. At this stage, the burden is on the District Attorney to prove beyond a reasonable doubt that the person still has a diagnosed mental disorder and represents a substantial danger of physical harm to others. Such extensions are for a one year period, but can potentially continue for the lifetime of the offender.