|Supermaximum security prisons have opened in many states within the U.S. in recent years. They are designed primarily for the purpose of incapacitating and deterring would-be dangerous inmates, with supporters claiming they result in reduced levels of prison violence. The proliferation of supermaximum prisons, however, has not been based on any credible social scientific research. This study attempts to partially fill this research void by examining the impact of the opening of a supermaximum prison in Illinois on aggregate levels of prison violence within the Illinois state prison system. An interrupted time series analysis using ARIMA modeling is conducted. The findings reveal no evidence to suggest the opening of Tamms had the desired impact on levels of inmate-on-inmate assaults. There is evidence, however, that the opening of Tamms resulted in a slight decrease in inmate-on-staff assaults. These findings are discussed in context of 1) other contemporaneous events occurring in the Illinois prison system that may have impacted prison violence levels - possible history effects and 2) a variety of measurement issues. Research and policy implications are highlighted.
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