In the case of United States v. Davis in 2018, the Supreme Court ruled on a provision of federal law that enhances penalties for using or carrying a firearm during crimes of violence or drug trafficking offenses. The defendants, Maurice Davis and Andre Glover, were convicted under this statute after committing several robberies in Texas while armed with handguns. They challenged their convictions arguing that the phrase "crime of violence" was unconstitutionally vague as it could be interpreted too broadly and unpredictably. The Supreme Court agreed with them by a vote of 5-4 ruling that indeed, the term "crime of violence" is unconstitutionally vague because it fails to give ordinary people fair notice about what conduct is criminalized and invites arbitrary enforcement by leaving judges and juries guessing about its meaning. This decision upheld an earlier ruling from lower courts which had also found this part of federal law to be unconstitutional due to vagueness.

In the dissenting opinion for United States v. Davis, Justice Kavanaugh argued that the majority's decision to strike down a federal law as unconstitutionally vague was incorrect. He contended that this law, which increased penalties for using firearms during crimes of violence, had been applied thousands of times over 30 years without any issues regarding its vagueness arising until now. According to him, the statute is not vague because it clearly defines what constitutes a crime of violence and provides examples of such crimes. Furthermore, he stated that even if there were some ambiguity in certain cases about whether an offense qualifies as a "crime of violence," courts could resolve these doubts on case-by-case basis rather than declaring entire statute unconstitutional. The justice also expressed concern about potential implications on public safety due to invalidation of this important criminal law provision.