Can You Use Drugs In the Workplace Based on the Free Exercise Clause ?
In Employment Division, Department of Human Resources of Oregon v. Smith, 494 U.S. 872, 110 S. Ct. 1595, 108 L. Ed. 2d 876 (1990), the Supreme Court held that the Free Exercise Clause did not prohibit application of Oregon's drug laws to the ceremonial ingestion of peyote and, thus, the state could, consistent with that Clause, deny claimants unemployment compensation for work-related misconduct based on their use of the drug.
The Supreme Court stated:
The Free Exercise Clause of the First Amendment, which has been made applicable to the States by incorporation into the Fourteenth Amendment, provides that "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof...."
The free exercise of religion means, first and foremost, the right to believe and profess whatever religious doctrine one desires.
Thus, the First Amendment obviously excludes all "governmental regulation of religious beliefs as such."
The government may not compel affirmation of religious belief, punish the expression of religious doctrines it believes to be false, impose special disabilities on the basis of religious views or religious status, or lend its power to one or the other side in controversies over religious authority or dogma. Smith, 494 U.S. at 876-77.