An empirical analysis of the GBMI verdict indicates that the verdict is not functioning as expected. The NGRI verdict continues to be used in Michigan courts. Three additional conclusions can be drawn from the study. First, most defendants found GBMI would probably have received guilty verdicts in the absence of the GBMI statute. Second, although the verdict was designed for jury trials, over 60 percent of those defendants found GBMI have come through plea bargains and another 20 percent have come from bench trials. Finally, the use of a State-operated Center for Forensic Psychiatry is an influential factor in any case in which insanity is raised as a defense. For this reason, States that do not have a facility like Michigan's forensic center may not have the same experience with the GBMI statute as Michigan. A total of 140 notes and appended tables and graphs are supplied. (Author summary modified)