Historically, there have been a disproportionate number of people with mental disorders involved in the criminal justice system. According to the State Justice Institute, 44 percent of people incarcerated in jail and 37 percent of people incarcerated in prison have been told by a mental health professional that they had a mental disorder, compared to about 19 percent of U.S. adults overall.  Many complex reasons for this disparity persist, such as systemic oppression and personal bias discussed throughout the text. Alongside these reasons, the study of criminal justice must consider people with mental disorders, including their diagnoses, assessment, and treatment, within this system

This chapter provides an overview of mental disorders commonly seen when working in the criminal justice field. In this chapter, we will also outline available assessments that diagnose, treat, and place people with mental and substance use disorders in the most appropriate programming and services. This chapter will explore the complex parallels between who society chooses to identify as a victim and as an offender. Lastly, the relationship between mental disorders and criminality will be discussed. Rather than stigmatizing criminality, this chapter aims to understand how to best work with criminality while treating the mental disorder.