arose from changing public attitudes; the American populace was more educated, tolerant, and willing to accept unorthodox behavior. Separation of church and state Legal battles concerning the separation of church and state originated in laws dating to 1938, which required religious instruction in school or provided state funding for religious schools. The Catholic church was a leading proponent of such laws, and the primary opponents (the "separationists") were the ACLU, Americans United for Separation of Church and State, and the American Jewish Congress. The ACLU led the challenge in the 1947 Everson v. Board of Education case, in which Justice Hugo Black wrote "[t]he First Amendment has erected a wall between church and state.... That wall must be kept high and impregnable." It was not clear that the Bill of Rights forbid state governments from supporting religious education, and strong legal arguments were made by religious proponents, arguing that the Supreme Court should not act as a "national school board", and that the Constitution did not govern social issues. However, the ACLU and other advocates of church/state separation persuaded the Court to declare such activities unconstitutional. Historian Samuel Walker writes that the ACLU's "greatest impact on American life" was its role in persuading the Supreme Court to "constitutionalize" so many public controversies. In 1948, the ACLU prevailed in the McCollum v. Board of Education case, which challenged public school religious classes taught by clergy paid for by private funds. The ACLU also won cases challenging schools in New Mexico that were taught by clergy and had crucifixes hanging in the classrooms. In the 1960s, the ACLU, in response to member insistence, turned its attention to the in-class promotion of religion. In 1960, 42 percent of American schools included Bible reading. In 1962, the ACLU published a policy statement condemning in-school prayers, observation of religious holidays, and Bible reading. The Supreme Court concurred with the ACLU's position when it prohibited New York's in-school prayers in the 1962 Engel v. Vitale decision. Religious factions across the country rebelled against the anti-prayer decisions, leading them to propose the School Prayer Constitutional Amendment, which declared in-school prayer legal. The ACLU participated in a lobbying effort against the amendment, and the 1966 congressional vote failed to obtain the required two-thirds majority. However, not all cases were victories; ACLU lost cases in 1949 and 1961 which challenged state laws requiring commercial businesses to close on Sunday,