Aguilar v. Felton
In Aguilar v. Felton, 473 U.S. 402, 105 S.Ct. 3232, 87 L.Ed.2d 290 (1985), the Court reaffirmed the continuing vitality of the "excessive entanglement" prong of the Lemon test.
Aguilar involved a challenge to New York City's provision of funding for public school instructors who taught remedial classes to private school students in private school classrooms. An overwhelming majority of the participating private schools were religiously affiliated.
New York City adopted a supervisory system designed to monitor the classes to ensure that public funds were not used to inculcate religious beliefs.
In holding that New York City's program violated the Establishment Clause, the Court stated:
This pervasive monitoring by public authorities in the sectarian schools infringes precisely those Establishment Clause values at the root of the prohibition of excessive entanglement. Agents of the city must visit and inspect the religious school regularly, alert for the subtle or overt presence of religious matter in Title I classes. In addition, the religious school must obey these same agents when they make determinations as to what is and what is not a "religious symbol" and thus off limits in a Title I classroom. In short, the religious school, which has a primary purpose of the advancement and preservation of a particular religion must endure the ongoing presence of state personnel whose primary purpose is to monitor teachers and students in an attempt to guard against the infiltration of religious thought. (Id. at 413, 105 S.Ct. at 3238.)