Although bail reform reduces jail census, whether or not its effects extend to incarcerated individuals with mental illness is unknown. Using a novel high-sensitivity measure of serious mental illness (SMI) from jail-based electronic health records, we conducted an interrupted time series analysis assessing the impact of Illinois bail reform on total jail registrations and the nested subset with SMI ± co-occurring substance use disorder (SUD). Compared with a decline in total jail registrations, admission of individuals with SMI ± SUD showed no decline. Consequently, the proportion of admissions involving SMI increased between 2015 and 2019 from 26% to 35%. Intentional efforts involving cooperation by the health, social services, and justice sectors are needed to translate the impact of bail reform onto the population experiencing SMI.
Keywords: co-occurring disorder; decarceration; mental health diversion; public health; serious mental illness.