Reynolds v. United States
From Conservapedia
Reynolds v. United States (1878) held that it was not a defense to a criminal indictment (for polygamy) to cite a religious duty (to the Mormon Church).
The case is significant in that unlike the court case Everson v. Board of Education, which relies solely on eight words taken out of context, Reynolds cited multiple clauses from the Danbury Letter in order to make a more thorough judicial reasoning.