Mueller v. Allen

The Court affirmed the ruling of the lower court. In his opinion, Justice Rehnquist acknowledged that "Today's case is no exception to our oft-repeated statement that the Establishment Clause presents especially difficult questions of interpretation and application." But in 1971, in Lemon v. Kurtzman the Court created a test since adopted in other Establishment Clause cases. The so-called "Lemon test" subjects a law to three requirements: It must reflect a secular purpose; it must, in its primary effect, not advance nor inhibit religion; and it must avoid excessive government "entanglement" in religious practice. The Court used the Lemon test in Mueller and ruled in favor of the Minnesota tax law.

On the first point of the test, Rehnquist wrote that the law was clearly "secular and understandable," as its goal was to help parents pay for education costs. Helping parents with those costs served the greater good by ensuring well educated citizens. Rehnquist further reasoned the existence of private schools helped lower public schooling expenses for taxpayers.

For the second point, Rehnquist wrote, "The deduction is available for educational expenses incurred by all parties, including those whose children attend public schools and those whose children attend nonsectarian private schools or sectarian private schools." By helping so many groups, the law did not advance religion.

The ruling in Mueller differed from that of Committee for Public Education and Religious Liberty v. Nyquist (1973), in which the Court struck down New York tax laws that helped only parents who sent their children to private, mostly parochial, schools. Mueller and the other petitioners cited Nyquist, arguing that the Minnesota law had a similar effect as the laws that were prohibited in New York. As their statistics showed, the Minnesota law in practice helped subsidize religious education. The Court, however, was not swayed by the numbers and largely dismissed them in their decision.

Finally, on the third point, the Court held that the Minnesota tax did not "excessively entangle" the state with religion, even though the state might have to decide which text books were secular and which were sectarian. Previous rulings had found that making such evaluations did not violate the Establishment Clause.