In the case of Larry Zobrest, et ux., et al. v. Catalina Foothills School District (1992), the Supreme Court ruled in favor of Zobrest, stating that a public school district providing a sign language interpreter to a deaf student attending a parochial school did not violate the Establishment Clause of the First Amendment. The parents of James Zobrest, who was deaf, sued Catalina Foothills School District after it refused to provide an interpreter for their son at his Catholic high school under Individuals with Disabilities Education Act (IDEA). The court held that since IDEA created a neutral government program disbursing aid not to schools but directly and only to individual disabled children defined without reference to religion and assistance provided under such program is available on equal basis whether child attends religious or secular private or public school; there was no violation against establishment clause.

In the dissenting opinion for Zobrest v. Catalina Foothills School District, Justice Blackmun argued that providing a publicly funded sign language interpreter to a deaf student attending a religious school violated the Establishment Clause of the First Amendment. He contended that this was not merely an instance of accommodating religion but rather constituted direct government support and promotion of religious indoctrination. The interpreter's presence in parochial classrooms, he noted, would inevitably involve conveying religious doctrine because they are required to translate everything said in class including prayers or teachings about faith. This arrangement thus amounted to state-sponsored instruction in religion which is constitutionally impermissible according to his interpretation of precedent cases like Lemon v Kurtzman (1971). Furthermore, he expressed concern over potential entanglement issues as public employees might have difficulty distinguishing between secular and sectarian content while interpreting at such schools.