The presence of large numbers of mentally ill people in prisons and jails has aroused concern that these settings are becoming de facto mental institutions, and that they are unprepared to meet the multiple service needs of this population (McNeil et al., 2005; National Public Radio [NPR] Staff, 2013; Williams, 2015). Others declare that homeless people are unfairly criminalized for attempts to obtain food, shelter, or medical attention and are inappropriately charged by the criminal justice system. A national study of nearly 7,000 jail inmates found that about 15 percent reported an episode of homelessness in the previous year. Compared to the larger, non-homeless group, those who had been homeless were more likely to have been arrested for a property crime. They were also more likely to have had criminal justice involvement in the past for both violent and nonviolent offenses. Other distinguishing characteristics of homeless individuals included mental health and substance abuse problems, less education, and unemployment (Greenberg & Rosenheck, 2008).
Conduct disorder in the early lives of homeless people with severe mental illness increases the risk of later homelessness (Caton et al., 1994; Caton et al., 1995; North et al., 1998) and criminal justice involvement (Desai et al., 2000). A systematic review of 15 studies of criminal behavior and victimization among homeless individuals with severe mental illness revealed that lifetime arrest rates ranged from 62.9 percent to 90 percent, conviction rates ranged from 48 percent to 67 percent, and incarceration rates ranged from 21.1 percent to 80 percent (Roy et al., 2014). A study linking mental health and jail records allowed researchers to compare people with mental illness who experienced incarceration with those who did not. The risk factors for incarceration included having had a previous incarceration, co-occurring substance use disorder, being male, and being homeless (Hawthorne et al., 2012). Another study of predictors of incarceration among urban adults with co-occurring severe mental illness and substance use disorder found that having had a prior incarceration predicted new episodes of incarceration during a three-year study period. A decreased likelihood of incarceration was found among those who had forged friendships with individuals who did not use substances, and those who were engaged in substance abuse treatment (Luciano et al., 2014).