In a closely watched religious rights case, the U.S. Supreme Court ruled unanimously Tuesday that an Arkansas prisoner must be allowed to grow a half-inch beard in accordance with his religion.

Federal law bars public institutions such as prisons from imposing a substantial and unjustified burden on the free exercise of religion. In this case, a prisoner named Gregory Holt had converted to Islam and sought permission to grow a half-inch beard, citing the tenets of his faith. The state refused the request, citing security concerns — that the beard, for instance, could be used to hide contraband.

Justice Samuel Alito, writing for the court, called the state's justifications "hard to swallow." He noted that prison systems in the vast majority of states, and in the federal system, all allow prisoners to grow beards. And he pointed to the fact that prisoners in Arkansas are allowed to grow hair on their head and wear clothes — more plausible places to hide contraband.

Nevertheless, prisoners are not required to go about "bald, barefoot or naked," he wrote.

"When so many prisons offer an accommodation," the court said, "a prison must, at a minimum, offer persuasive reasons why it believes that it must take a different course," and Arkansas failed to make that showing here.

Justice Ruth Bader Ginsburg wrote a short but pointed concurring opinion noting the difference between the prison beards case, and last June's highly controversial Supreme Court decision allowing for-profit corporations that object to contraception to bar contraceptive insurance coverage for their employees. The difference, she said, is that in this case, accommodating the prisoner's religious beliefs "would not detrimentally affect others who do not share [his] belief."

Justice Sonia Sotomayor joined the concurrence and also wrote separately to stress the danger of the prison environment. She emphasized that some deference is due to prison officials who design rules for that environment and can offer a "plausible explanation for their chosen policy that is supported by whatever evidence is reasonably available to them."

Copyright 2016 NPR. To see more, visit