Does Mens Rea Matter?

Does mens rea matter to the criminal legal system? Our study addresses this question by performing the first-ever empirical analysis of a culpable mental state’s impact on administration of a criminal statute. We focus on the U.S. Supreme Court’s 2019 decision in Rehaif v. United States, which applied a culpable knowledge requirement to the federal felon-in-possession statute, 18 U.S.C. § 922(g). Prior to Rehaif, federal courts viewed § 922(g)’s critical legal status element—whether a firearm or ammunition possessor meets the conditions for one of nine prohibited categories—as being subject to strict liability. After Rehaif, the government must now prove that the target of a § 922(g) prosecution was aware of their prohibited legal status to secure a conviction. Our study provides reason to believe that this new mens rea requirement significantly reduced the number of defendants charged with § 922(g) per month, the number of § 922(g) charges filed each month, the number of § 922(g) charges per defendant, and the likelihood that any individual charge of § 922(g) would be adjudicated guilty. We estimate these charging reductions prevented 2,365.32 convictions and eliminated 8,419.06 years of prison sentences for § 922(g) violations during the eight-month period between the issuance of the Rehaif opinion and the start of the COVID-19 pandemic, which severely disrupted federal criminal prosecutions. At the same time, we also find that the government’s § 922(g) conviction rate—the likelihood that someone charged by federal prosecutors with violating § 922(g) will ultimately be found guilty—did not change after Rehaif. All told, our study indicates that mens rea can constrain prosecutorial discretion, lower convictions, and reduce punishment without bringing criminal administration to a halt.