Employment Div. v. Smith
In Employment Division v. Smith, 494 U.S. 872 (1990), U.S. Supreme Court Justice Antonin Scalia wrote for the Court in declaring that a generally applicable law that is neutral on its face can be enforced against a claim of the exercise of religion under the First Amendment, provided there is no simultaneous infringement of another constitutional right.
Specifically, the Court upheld the denial of unemployment benefits by the state of Oregon to two Native Americans who had been fired from their jobs at a rehabilitation clinic after testing positive for an hallucinatory drug associated with peyote, which can be taken as part of an Indian ceremony. In effect, the Court denied their claim under the free exercise clause of the First Amendment.