LINCOLN, Neb. (AP) — A man serving a life sentence for murder in Nebraska has asked a judge to let him keep racy books that were confiscated after prison officials banned pornography.

Danny Robinson Jr. filed a lawsuit last week arguing that the policy is unconstitutionally vague and discriminatory because it gives prison staffers too much discretion to decide what qualifies as pornography.

He argued that prison staffers have enforced the policy with a bias against straight men by confiscating magazines with women in swimsuits while still allowing “muscle mags” with bare-chested men that could arouse gay men or female inmates.

“In an environment of desperately horny and sexually frustrated men, (prison officials) are blatantly provoking them to have sex with each other to satisfy their sexual urges,” Robinson wrote in the lawsuit.

The policy, which went into effect Jan. 8, 2018, bars materials that show or depict sexual acts and nudity of either gender. Previously, only publications or items likely to incite violent or illegal activity, including materials that advocate or depict violent or illegal sexual activity, had been barred.

Robinson’s lawsuit is the latest effort by an inmate to regain access to pornography as more prisons nationally seek to restrict sexual content. Last year, 58 Iowa inmates filed a federal lawsuit to challenge a new law that effectively shut down designated “pornography reading rooms” in the state’s prisons.

Prisoners in Michigan protested a similar law in 2011 with an unsuccessful letter-writing campaign to state officials, arguing that the ban violated their First Amendment rights.

In 2015, a judge in Virginia ruled that the Virginia Beach Sheriff’s Office had an unconstitutional, over-broad policy on explicit materials after a prisoners’ rights magazine filed a lawsuit because copies weren’t being delivered to inmates.

Jail officials rejected the magazines because they contained ads promoting pen pal services and photos of nude models with stars covering their “private parts.” The magazine later removed those ads.

However, courts have generally sided with prison officials. Prison officials argue that banning pornography promotes safety and a rehabilitative environment and helps keep the material out of the hands of sex offenders.