An initial holding cell. (Dan Morse/The Washington Post)

Advocates for prisoners in Maryland called on state officials Thursday to rescind a new policy that they say severely restricts access to books for inmates and is unconstitutional.

In a letter to state prison officials, the American Civil Liberties Union characterizes the limits on book ordering as a “virtual book ban” that denies more than 20,000 Maryland inmates access to “the overwhelming majority of books in existence, and prevent those who wish to communicate with them through books from doing so.”

The statewide policy announced in April restricts book orders to two private vendors with offerings that the ACLU describes as “extremely limited” in comparison with the millions of titles available through online booksellers and publishers.

The restrictions, the ACLU said, are an “irrational, arbitrary and an exaggerated response to security concerns” that also violate a First Amendment right to read and the rights of prisoners’ family members to stay in touch through gifts of books.

The seven-page letter addressed to Stephen Moyer, secretary of the Maryland Department of Public Safety and Correctional Services, requests a response from prison officials by June 11.

The secretary and department attorneys are reviewing the letter. Prison officials say the new policy is intended to reduce drug smuggling into state-run facilities, including through the pages of books. In recent years, officials have recovered thousands of strips of Suboxone, an FDA-approved medication that helps opiate addicts manage withdrawal symptoms.

“At this time, there is no intent to change the department’s decision, which ensures inmates have access to books in a safe manner,” spokesman Gerard Shields said in a written statement Thursday. “Drugs smuggled into our institutions fuel prison violence, and the safety of our officers, staff and those in our custody remains paramount.”

The thin, clear strips bearing Suboxone are easy to conceal and difficult to detect, but prison officials could not say how many of the strips that they found were hidden in books.

Under the policy, inmates may no longer receive books shipped from online retailers or sent by friends and relatives. They must instead purchase reading material from two prison-approved vendors, in some cases at a higher cost.

Criticism of the policy by Maryland inmates, their families and the ACLU comes after federal prison officials abruptly pulled a similar policy in place at three facilities that limited book purchases to a prison-approved vendor and imposed a 30 percent markup.

Advocates for inmates say the Maryland policy is overly broad because most book shipments are genuine attempts to make books available to prisoners – not to smuggle drugs. Limiting access to books, they say, will create more security threats by further isolating prisoners from contact with the outside world and adding to the monotony of prison life.

State-run facilities have 129,000 books in library collections, and the government spends about $16,000 each year for new books, in addition to receiving thousands of donated books. The two prison-approved vendors offer more than 15,000 titles.

But the ACLU letter lists more than a dozen popular or classic books that it could not locate from either vendor in the paperback format Maryland prisons require. Among the titles are J.D. Salinger’s “Catcher in the Rye;” Ralph Ellison’s “Invisible Man;” and J.K. Rowling’s Harry Potter books.

Until last month, D.C. resident Martina Hazelton had routinely ordered from online retailers to ship books directly to her husband, an inmate at the Western Correctional Institution in Cumberland, Md. The couple often read the same books simultaneously and discuss them by phone and in letters, and Hazelton picks topics that she says help her husband’s emotional and spiritual stability.

After learning about the new policy, Hazelton reviewed titles offered by the two vendors — Books & Things and Edward R. Hamilton. Missing from the listings, she said, were many of the books she has sent her husband, Eric, in the past year, including “Writing My Wrongs,” a memoir by Shaka Senghor in part about his 19 years in prison.

“The families who purchase books for their loved ones fill a gap DOC is not meeting,” Hazelton said of Maryland’s Division of Corrections. “We all feel like this is a blow.”