Objective: Some believe serious mental illness has been "criminalized." Effects of serious mental illness and substance abuse on criminal offenses were studied for 113 postbooking jail diversion participants and their nondiverted counterparts.
Methods: Raters read participants' and police report descriptions of criminal offenses and participants' explanations for them. Using 5-point scales, raters independently estimated whether an offense resulted directly or indirectly from serious mental illness or substance abuse.
Results: Serious mental illness and substance abuse had little effect on offenses. However, substance abuse led to a sizable minority of offenses and was more likely than mental illness to cause an offense.
Conclusions: Unless factors unique to serious mental illness can be specifically associated with behavior leading to incarceration, the criminalization hypothesis should be reconsidered in favor of more powerful risk factors for crime that are widespread in social settings of persons with serious mental illness.