The U.S. Supreme Court case Edwards v. Aguillard in 1986 revolved around a Louisiana law that required public schools to teach creationism if they taught evolution, with the aim of promoting academic freedom. The respondents, including parents and teachers, challenged this law arguing it violated the First Amendment's Establishment Clause which prohibits any law respecting an establishment of religion. The Supreme Court ruled in favor of Aguillard and others (7-2), stating that the Louisiana Law was indeed unconstitutional as it intended to advance a particular religion by requiring teaching creation science alongside evolutionary theory without clear educational objectives being served by such instruction. This decision reinforced the principle that state mandates must be secular in nature and not seek to promote or inhibit any religious beliefs within public education settings.

In the dissenting opinion of Edwards v. Aguillard, Justice Scalia, joined by Chief Justice Rehnquist, argued that the Louisiana law requiring balanced treatment between "creation science" and evolution did not violate the Establishment Clause. They believed it was a legitimate attempt to protect academic freedom rather than an endorsement of religion. The justices contended that there was no clear evidence showing religious motivation behind this legislation; instead they saw it as promoting educational fairness and objectivity in teaching scientific theories about human origins. Furthermore, they criticized the majority for overstepping their judicial role by making assumptions about legislative intent without substantial proof or explicit statements from lawmakers themselves.