(JTA) — The American Civil Liberties Union has warned the Wyoming Department of Corrections that prohibiting an Orthodox Jewish inmate from wearing a kippah violates his religious freedom.

The ACLU and the ACLU of Wyoming sent a letter on January 9 to the Wyoming Department of Corrections on behalf of inmate Clarence E. Fisher, saying that its refusal to allow Fisher to wear his kippah at all times violates the Religious Land Use and Institutionalized Persons Act of 2000, that allows prisoners to worship according to their religious beliefs.

The corrections department only allows a prisoner to wear a kippah in his own cell or during religious services.

The corrections department cited non-specific “security concerns” for its refusal to accede to Fisher’s request to wear a kippah at all times, in accordance with his religious beliefs, according to the ACLU.

The ACLU notes that prisoners can wear baseball caps and hats purchased at the prison commissary.

Jewish inmates in federal prisons are permitted to wear a kippah at all times, the ACLU noted.

The ACLU asked the corrections department to revise its policy.