Christians and defenders of religious freedom such as the American Center for Law and Justice cite attacks on Christmas (dubbed a "war on Christmas").[169][170][171] One controversy is the occurrence of Christmas trees being renamed Holiday trees.[170] In the United States there has been a tendency to replace the greeting Merry Christmas with Happy Holidays.[172] Groups such as the American Civil Liberties Union have initiated court cases to bar the display of images and other material referring to Christmas from public property, including schools.[173] Such groups argue that government-funded displays of Christmas imagery and traditions violate the First Amendment to the United States Constitution, which prohibits the establishment by Congress of a national religion.[174] In 1984, the U.S. Supreme Court ruled in Lynch vs. Donnelly that a Christmas display (which included a Nativity scene) owned and displayed by the city of Pawtucket, Rhode Island, did not violate the First Amendment.[175]