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Insanity acquittee outcomes in New Zealand


  • Jeremy Skipworth,

  • Phil Brinded,

  • David Chaplow,

  • Chris Frampton

Jeremy Skipworth, Deputy Director of Mental Health (Correspondence); David Chaplow, Director of Mental Health
Ministry of Health, Wellington, New Zealand. Email:

Phil Brinded, Clinical Director
Medlicott Unit and Regional Forensic Psychiatry Service, Canterbury District Health Board, Christchurch, New Zealand

Chris Frampton, Bio-statistician
Christchurch Clinical School of Medicine, Christchurch, New Zealand


Objective:  This paper examines clinical and forensic outcomes for defendants found not guilty by reason of insanity in New Zealand, and explores the implications for policy development and clinical rehabilitation in this population.

Method:  All insanity acquittees disposed of by the courts as special patients after 1976 and released before 2004 are described. Their duration of inpatient care, rates of reconviction and rehospitalization following release are examined. The high resolution rate for violent crime reported to police suggests that reconviction rates are a reasonable proxy for violent reoffending. Factors predicting duration of inpatient care and reoffending are analysed.

Results:  Severity of Index Offence was the only variable predicting duration of inpatient care of the 135 special patients. Offenders of more serious offences were securely detained for longer periods – averaging 6 years in the case of those charged with murder. Most patients were readmitted over the decade following discharge. Only 6% had violently reoffended 2 years after release into the community. Prior offending, age at release, ethnicity and gender predicted reoffending, but not diagnosis or duration of inpatient admission.

Conclusions:  Following discharge into the community, insanity acquittees are reconvicted of violent crimes at a very low rate, although readmission to hospital is common. It may be that insanity acquittees are initially detained in hospital longer than is clinically indicated, and that safe forensic community treatment can occur at an earlier stage of recovery without compromising public safety.