In January 2015, Randy Metcalf was involved in a bar-fight in Dubuque, Iowa, where he seriously hurt a man. Was he prosecuted for assault under state law? No. Because Metcalf allegedly shouted racial slurs during the fight, federal prosecutors indicted him for one count of violating the Hate Crimes Prevention Act of 2009 (HCPA): causing bodily injury “because of the actual or perceived race, color, religion, or national origin of any person.”

The HCPA was enacted under Section 2 of the Thirteenth Amendment, which authorizes Congress to enforce the Constitution’s ban on slavery—an authority the Supreme Court has extended to eliminating the “badges and incidents” of slavery. Before his trial—and ultimate conviction—Metcalf challenged the constitutionality of the HCPA, arguing that racially motivated violence does not fall within congressional authority.

The district court upheld the HCPA, however, deferring to Congress’s power to “rationally determine” what the badges and incidents of slavery are. Metcalf appealed his case to the U.S. Court of Appeals for the Eighth Circuit, where Cato has now filed an amicus brief that mirrors two previous ones we filed on the same issue in unrelated cases. We argue that the use of hate-crime laws to sweep intra-state criminal activity—here an allegedly racially motivated bar fight—into federal court has nothing to do with stamping out slavery, and therefore does not fall within Congress’s enumerated powers.

Not only are federal hate-crime laws constitutionally unsound, but, as George Zimmerman’s trial highlighted, they invite people dissatisfied with a state-court outcome to demand that the government retry unpopular defendants. That implicates one of our most fundamental liberties: protection from being prosecuted twice for the same act. Indeed, this protection from being placed in “double jeopardy” is explicitly enshrined in the text of the Fifth Amendment: “nor shall any person be subject for the same offense to be twice put in jeopardy of life or limb.”

In the 1920s, however, the Supreme Court recognized a “dual sovereignty” exception to the rule, permitting the federal government to prosecute defendants even after they had endured trial at the state level. This exception emanated from the Court’s narrow concern that weak state enforcement of prohibition laws would disrupt the federal government’s ability to bring bootleggers to justice. Once Prohibition ended, however, the dual-sovereignty exception did not. Not only did it survive, it has thrived in the face of the ever-expanding federalization of the criminal law—a body of law that has now grown so large the number of crimes it covers cannot be counted, exposing more and more people to federal criminal penalties for crimes traditionally reserved to the states to enforce through their police power.

The HCPA is a prominent example of the danger federal overcriminalization has wrought, and is indeed even more susceptible to abuse due to the highly emotional nature of the underlying offenses. Moreover, the HPCA’s coverage is so broad that almost any violent crime could be subject to double prosecution by the state and federal government—and indeed any rape could be seen as hating a particular sex.

In United States v. Metcalf, the Eighth Circuit should end this practice, find the HCPA unconstitutional, and let state authorities deal with the Randy Metcalfs of the world.