Objective: Few studies have addressed use of resources in police interventions involving individuals with mental illness. The time police officers spend on interventions is a straightforward measure with significant administrative weight, given that it addresses human resource allocation. This study compared the characteristics of police interventions involving individuals with mental illness and a control sample of individuals without mental illness.

Methods: A total of 6,128 police interventions in Montreal, Québec, were analyzed by using a retrospective analysis of police intervention logs from three days in 2006. Interventions involving citizens with (N=272) and without (N=5,856) mental illness were compared by reason for the intervention, the use of arrest, and the use of police resources.

Results: Police interventions involving individuals with mental illness were less likely than those involving individuals without mental illness to be related to more severe offenses. However, interventions for minor offenses were more likely to lead to arrest when they involved citizens with mental illness. Interventions for reasons of equal severity were twice as likely to lead to arrest if the citizen involved had a mental illness. After controlling for the use of arrest and the severity of the situation, the analysis showed that police interventions involving individuals with mental illness used 87% more resources than interventions involving individuals without mental illness.

Conclusions: Future studies using administrative police data sets could investigate the use of resources and division of costs involved in new programs or partnerships to better address the interface of criminal justice and mental health care.