In proposing a voucher system that would subsidize the tuition of children who choose parochial schools, the Bush Administration is confronting one of the nation's sacrosanct principles: the First Amendment's stricture against "establishment of religion" creates a wall between church and state. That hurdle, while high, may not be impossible to surmount. Over the years the Supreme Court has wrestled with the distinction between direct funding of religious institutions, which is forbidden, and indirect aid that is designed to serve a secular purpose, which may be permissible.
One guiding interpretation is the court's 1947 Everson v. Board of Education decision, which...