O'Lone v. Estate of Shabazz, 482 U.S. 342 (1987), was a U.S. Supreme Court decision involving the constitutionality of prison regulations. The court ruled that the prison regulations were not a violation of the Free Exercise Clause of the First Amendment of the U.S. Constitution to deprive an inmate of attending a religious service for "legitimate penological interests."

Prison inmates of the Islamic faith filed suit, alleging that two New Jersey prison policies violated their First Amendment right to freely exercise their religion by preventing them from attending Friday afternoon Muslim congregational services.

The first policy required inmates to work outside the buildings where they were housed and where the religious service was held. The second policy prohibited inmates assigned to outside work from returning to those buildings during the day.

The district court ruled that the policies did not violate the Constitution. On appeal, the U.S. Court of Appeals for the Third Circuit vacated the district court’s judgment and remanded the case for further proceedings.

The Court reversed the decision, with Justice Rehnquist delivering the majority opinion.

The Court held that the Circuit Court erred by placing the burden on prison officials to disprove the availability of alternatives and by failing to grant the deference the Constitution affords to prison administrators’ judgment. It also found the two prison policies “reasonably related to legitimate penological objectives” and not in violation of the First Amendment. The Court stated that it would not substitute its judgment for that of prison administrators.

• Rachanow, Shelly S. (1998). "The Effect of O'Lone v. Estate of Shabazz on the Free Exercise Rights of Prisoners". Journal of Church & State. 40: 125–148. doi:10.1093/jcs/40.1.125. ISSN 0021-969X.
• Rigoli, L. M. (1990). ""Power Exercised in the Shadows": O'Lone v. Shabazz as a Signal to the Court's Return to Interpretivism in Institutional Reform Litigation". New England Journal on Crime and Civil Confinement. 16: 141.

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• Text of O'Lone v. Estate of Shabazz, 482 U.S. 342 (1987) is available from: CourtListener Findlaw Google Scholar Justia Library of Congress Oyez (oral argument audio)