Prisons can restrict the rights of inmates to nerd out, a federal appeals court has found.

In an opinion issued on Monday , a three-judge panel of the United States Court of Appeals for the Seventh Circuit rejected the claims in a lawsuit challenging a ban on the game Dungeons & Dragons by the Waupun Correctional Institution in Wisconsin.

The suit was brought by a prisoner, Kevin T. Singer, who argued that his First Amendment and 14th Amendment rights were violated by the prison’s decision to ban the game and confiscate his books and other materials, including a 96-page handwritten manuscript he had created for the game.

Mr. Singer, “a D&D enthusiast since childhood,” according to the court’s opinion, was sentenced to life in prison in 2002 for bludgeoning and stabbing his sister’s boyfriend to death.

Prison officials said they had banned the game at the recommendation of the prison’s specialist on gangs, who said it could lead to gang behavior and fantasies about escape.

Dungeons & Dragons could “foster an inmate’s obsession with escaping from the real-life correctional environment, fostering hostility, violence and escape behavior,” prison officials said in court. That could make it more difficult to rehabilitate prisoners and could endanger public safety, they said.

The court, which is based in Chicago, acknowledged that there was no evidence of marauding gangs spurred to their acts of destruction by swinging imaginary mauls, but it ruled nonetheless that the prison’s decision was “rationally related” to legitimate goals of prison administration.

“We are pleased with the ruling,” said John Dipko, a spokesman for the Wisconsin Department of Corrections, who added that the prison rules “enable us to continue our mission of keeping our state safe.”

News of the decision spread quickly though the network of blogs that discuss such games and to those devoted to the law, where many commentators revealed perhaps more of their own history as gamers than they might have intended. On The Volokh Conspiracy, a legal blog, a particularly rollicking discussion ensued, kicked off with a post by Ilya Somin, an associate professor of law at George Mason University, who asked, “Should prisons ban ‘The Count of Monte Cristo’ on the grounds that it might encourage escape attempts?”

In an interview, Professor Somin said the prison’s action was reminiscent of a media frenzy in the 1980s surrounding the supposedly pernicious effects of gaming. “Ideally, you should really have more evidence that there is a genuine harm before you restrict something,” he said.

The comments accompanying Professor Somin’s post ranged from hoots of outrage over the ban to constitutionally nuanced discussion, but they showed that there were many lawyers who at some point owned a pouch with some dice of more than six sides. And none of them seemed to think that the risk to the nation’s prisons could be found in the works of Gary Gygax or other creators of the genre.

As Andrew Oh-Willeke, a lawyer in Denver, wrote, “If more inmates were über-nerdy D&D players, life would be good.”