Private school voucher programs raise a number of legal issues, and many have faced court challenges. Voucher programs may violate a state constitution's education clause, including a state's obligation to adequately fund public schools or to provide a uniform system of public schools, and other important state constitutional protections.

Voucher lawsuits have also been based on violations of the First Amendment to the U.S. Constitution as well as state constitutional provisions, known as Blaine Amendments or no-aid clauses, that prohibit public funding of religious institutions. Other voucher lawsuits have focused on students' civil rights guarantees.