Guilty but Mentally Ill

(by Andrew Garofolo)

Overview of the GBMI

Not all defendants meet the criteria for a not guilty by reason of insanity plea, but clearly have some sort of mental illness at the time of the crime.

  • Defendants who plea not guilty by reason of insanity usually lack two things. One is a lack of appreciation for the wrongness of their actions. The other is a lack of understanding of the consequences of their actions (Kutys, 2009).
  • Defendants who only lack one of these will a lot of times plea guilty but mentally ill (GBMI). This resembles a standard guilty plea, except it expresses the fact that the defendant is in need of mental health treatment in addition to punishment (Kutys, 2009).

History and Background of the GBMI

The GBMI was first adopted in Michigan in 1975. It stemmed from the 1974 case of People vs. McQuillan

  • In this case, it was ruled that defendants found not guilty by reason of insanity would be placed into institutions for the criminally insane, and once they were found to be mentally sane, they were to be released (People vs. McQuillan, 1974).
  • The problem with this is that two people that were released went on to commit another crime.
  • Thus, the guilty but mentally ill (GBMI) was adopted in several states.

To be pronounced guilty but mentally ill results in conviction and a criminal sentence. The defendant is then evaluated for psychiatric treatment. If treatment is warranted, the defendant is hospitalized for that purpose. When they are discharged, they serve remainder of sentence in prison (Borum & Fulero, 1999).



Borum, R., & Fulero, S. (1999).  Empirical Research on the Insanity Defense and attempted reforms:  Evidence toward Informed Policy.  Law and Human Behavior, 23(3), 375-394.

Kutys, J. (2009). GBMI vs. NGRI: An Annotated Bibliography. The Jury Expert. Retrieved from

People vs. McQuillan. (1974). Supreme Court of Michigan. Retrieved from


Leave a Reply

Your email address will not be published. Required fields are marked *