Zobrest v. Catalina Foothills School District

The Lemon test, named for the Supreme Court case Lemon v. Kurtzman, uses a three-part test to determine if laws or government activities are considered unconstitutional. For instance, to determine if parochial school aid is constitutional, the test asks if the aid is for a religious purpose, promotes a religion, or requires excessive entanglement between government and religion. The importance of using the Lemon test to determine the constitutionality of parochial school aid can be seen in the impact that the result has on the large number of U.S. citizens who send their children to private schools.

At the time the Lemon test was adopted by the Court in 1971, there were 36 states considering measures to help parochial schools, according to a 10 July 1971, article in The New Republic. The article went on to state that 25 percent of Rhode Island's elementary-age children were enrolled in private schools and that 95 percent of those were parochial. In Pennsylvania, the article states, 20 percent of elementary pupils were in private school with 98 of those parochial institutions.