Mandatory Sexual Assault Kit Testing Policies and Arrest Trends: A Natural Experiment

Abstract

The present study employs a quasi-experimental design to evaluate the effects of a mandatory sexual assault kit (SAK) testing policy on rape arrests in a large western US jurisdiction. We use a Bayesian structural time-series model and monthly data on arrests for rape from 2010 through 2019. In the post-implementation period, we observed a downward trend in the arrest rate for rape. Based on the results, the most conservative interpretation of our findings is that the policy implementation did not affect rape arrest rates. While mandatory SAK testing policies are often advocated for based on the belief that they will increase arrest rates for sexual assault (among other proposed benefits), we add to growing empirical evidence that policy interventions beyond mandatory SAK testing are needed to increase arrest rates for sexual assault. Jurisdictions that currently use mandatory SAK testing policies are encouraged to assess stakeholders’ experiences to proactively address resource allocation, consider other policies that may increase accountability for sexual assault offenders, and utilize victim service providers to support other measures of success with victims in instances where no arrest is made.

Keywords:

• Bayesian structural time-series
• policing
• policy evaluation
• sexual assault kit
• victimization

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 The frequentist analog to a credible interval is a confidence interval, yet the two concepts are statistically different. In a frequentist paradigm, confidence intervals are based on repeated sampling theory. A 95% confidence interval indicates that 95 out of 100 replications of exactly the same experiment will capture the fixed, but unknown, regression coefficient. A credible interval can be interpreted as the probability that the population parameter is between the upper and lower bounds of the credible interval, based on the available information (Van de Schoot & Depaoli, 2014).

2 While not statistically significant, much like our analysis, Davis et al. (2020) finds a general decrease in the sexual assault arrest rate after the mandatory testing policy implementation.

Additional information

Notes on contributors

Scott M. Mourtgos

Scott M. Mourtgos is a PhD student in the Department of Political Science at the University of Utah. His research focuses on policing and criminal justice policy.

Ian T. Adams

Ian T. Adams is a PhD candidate in the Department of Political Science at the University of Utah. His research interests include body-worn cameras, policing policy, and public workplace surveillance.

Justin Nix

Justin Nix is an associate professor in the School of Criminology and Criminal Justice at the University of Nebraska Omaha. His research interests include police legitimacy and officer-involved shootings.

Tara Richards

Tara N. Richards is an Associate Professor in the School of Criminology and Criminal Justice at the University of Nebraska at Omaha. She received her PhD in Criminology from the University of South Florida. Her research is centered in victimology, with recent articles appearing in Justice Quarterly, Law and Human Behavior, and Child Abuse & Neglect.