The prison population in the United States has risen over the past 50 years, to 1.4 million, from 200,000. Substance offenses have been the leading cause of incarceration in state and federal jails and prisons. Yet many individuals who have a substance use disorder (SUD) struggle to receive treatment. One of the most effective tactics for both health outcomes for individuals and financial savings for states may be to increase access to treatment options for justice-involved individuals. In this paper, we discuss the current status of SUD treatment within jails and prisons, as well as existing rehabilitative policies and programs that could improve treatment. We also discuss the existing funding sources for SUD treatment and the potential to expand both funding and treatment.