Lemon v. Kurtzman

Lemon v. Kurtzman, 403 U.S. 602 (1971), was a case argued before the Supreme Court of the United States. The court ruled in an 8–0 decision that Pennsylvania's Nonpublic Elementary and Secondary Education Act (represented through David Kurtzman) from 1968 was unconstitutional and in an 8–1 decision that Rhode Island's 1969 Salary Supplement Act was unconstitutional, violating the Establishment Clause of the First Amendment. The act allowed the Superintendent of Public Schools to reimburse private schools (mostly Catholic) for the salaries of teachers who taught in these private elementary schools from public textbooks and with public instructional materials. "Lemon" was a major precedent in federal and local courts until it was effectively overturned by "Kennedy v. Bremerton School District" in 2022.
"Lemon" test.
The Court's decision in this case established the ""Lemon" test" (named after the lead plaintiff Alton Lemon), which details legislation concerning religion. It is threefold:
If any of these prongs is violated, the government's action is deemed unconstitutional under the Establishment Clause of the First Amendment to the United States Constitution. In the 1985 case "Wallace v. Jaffree" the Supreme Court further stated that the effect prong and the entanglement prong do not need to be examined, if the law in question doesn't have an obvious secular purpose. In "Corporation of Presiding Bishop of Church of Jesus Christ of Latter-day Saints v. Amos" (1987) the Supreme Court noted that the purpose prong's requirement of a secular legislative purpose doesn't mean that the law's purpose must be unrelated to religion, because this would amount to a requirement, in the words of "Zorach v. Clauson", 343 U. S. 306 (1952), at 314, "that the government show a callous indifference to religious groups." Instead, ""Lemon"'s 'purpose' requirement aims at preventing the relevant governmental decisionmaker – here, Congress – from abandoning neutrality and acting with the intent of promoting a particular point of view in religious matters." As observed by the Supreme Court in "McCreary County v. American Civil Liberties Union" (2005), "When the government acts with the ostensible and predominant purpose of advancing religion, it violates that central Establishment Clause value of official religious neutrality, there being no neutrality when the government’s ostensible object is to take sides." 
The act stipulated that "eligible teachers must teach only courses offered in the public schools, using only materials used in the public schools, and must agree not to teach courses in religion." Still, a three-judge panel found 25% of the State's elementary students attended private schools, about 95% of those attended Roman Catholic schools, and the sole beneficiaries under the act were 250 teachers at Roman Catholic schools.
The court found that the parochial school system was "an integral part of the religious mission of the Catholic Church", and held that the Act fostered "excessive entanglement" between government and religion, thus violating the Establishment Clause.
"Agostini v. Felton" modification.
The "Lemon" test was modified, according to the First Amendment Center, in the 1997 case "Agostini v. Felton" in which the U.S. Supreme Court combined the effect prong and the entanglement prong. This resulted in an unchanged purpose prong and a modified effect prong. "The Court in "Agostini" identified three primary criteria for determining whether a government action has a primary effect of advancing religion: 1) government indoctrination, 2) defining the recipients of government benefits based on religion, and 3) excessive entanglement between government and religion."
Later use.
Conservative justices, such as Clarence Thomas and Antonin Scalia, have criticized the application of the "Lemon" test. The test was compared to a "ghoul in a late night horror movie" by Justice Scalia in "Lamb's Chapel v. Center Moriches Union Free School District" (1993). 
The Supreme Court itself has applied the "Lemon" test in "Santa Fe Independent School Dist. v. Doe" (2000), while in "McCreary County v. American Civil Liberties Union" (2005) the court did not overturn the "Lemon" test, even though it was urged to do so by the petitioner.
The test was also central to "Kitzmiller v. Dover", a 2005 intelligent design case before the United States District Court for the Middle District of Pennsylvania.
The Fourth Circuit Court of Appeals applied the test in "Int'l Refugee Assistance Project v. Trump" (2017) upholding a preliminary injunction against President Donald Trump's executive order banning immigration from certain majority-Muslim countries.
In concurring opinions to "The American Legion v. American Humanist Association" (2019), some of the Court's more conservative justices heavily criticized the "Lemon" test. Justice Samuel Alito stated that the "Lemon" test had "shortcomings" and that "as Establishment Clause cases involving a great array of laws and practices came to the Court, it became more and more apparent that the "Lemon" test could not resolve them." Justice Brett Kavanaugh noted that the Court "no longer applies the old test articulated in "Lemon v. Kurtzman"" and said that "the Court’s decisions over the span of several decades demonstrate that the "Lemon" test is not good law and does not apply to Establishment Clause cases." Although the Court did not overrule "Lemon v. Kurtzman" in "American Legion v. American Humanist Association", Justice Thomas stated that he "would take the logical next step and overrule the "Lemon" test in all contexts" because "the "Lemon" test is not good law." Additionally, Justice Neil Gorsuch called "Lemon v. Kurtzman" a "misadventure" and claimed that it has now been "shelved" by the Court. Justice Elena Kagan, however, defended the "Lemon" test, stating that "although I agree that rigid application of the "Lemon" test does not solve every Establishment Clause problem, I think that test's focus on purposes and effects is crucial in evaluating government action in this sphere—as this very suit shows."
"Kennedy v. Bremerton School District".
Members of the Supreme Court have long criticized "Lemon." In June 2022, the Supreme Court "de facto" overturned "Lemon" in "Kennedy v. Bremerton School District". While Associate Justice Neil Gorsuch's majority opinion did not explicitly overturn "Lemon", it instructed lower courts to disregard "Lemon" in favor of a new standard for evaluating religious actions in a public school. Associate Justice Sonia Sotomayor's dissent, however, explicitly stated that "Kennedy" had overturned "Lemon".