BART workers remove a man atop a train during a protest at the Civic Center station in San Francisco last month. Authorities closed the station where demonstrators condemned the fatal shooting of a man by transit police the week before.

For apparently the first time in the United States, a government agency shuttered mobile-internet and phone service in a bid to quash a demonstration — the same type of speech suppression exercised by Middle Eastern tyrannies to quell dissent.

Thursday’s move by Bay Area Rapid Transit authorities was greeted by an uproar of comparisons to Egypt and Libya. The hacking collective Anonymous responded in typical form over the weekend by defacing the agency’s website, and stealing and releasing the private account information of some 2,000 San Francisco–area transit riders.

The controversy began when officials removed the power to underground service towers Thursday at four San Francisco stations in anticipation of a planned protest — which did not materialize — over the shooting death of a knife-wielding man by BART police last month.

Some constitutional scholars are likening BART’s actions to an unlawful suppression of First Amendment speech — a digital form of prior restraint. Others, however, say BART’s move would probably survive a court challenge, and will likely be copied by other government agencies as the use of mobile technology and social networking by protesters grows.

“You have the right to speak,” Damon Dunn, a First Amendment lawyer in Chicago, said in a telephone interview. “I don’t think you have the right to leverage your speech through technology that you don’t necessarily control yourself.”

An earlier BART protest in July resulted in a major disruption of rush-hour service, as some protesters even climbed atop cars at the Civic Center station.

“The interruption of cell phone service was done Thursday to prevent what could have been a dangerous situation. It’s one of the tactics we have at our disposal. We may use it; we may not. And I’m not sure we would necessarily let anyone know in advance either way,” BART spokesman Jim Allison said.

The Electronic Frontier Foundation said BART’s actions constituted an unconstitutional breach of protesters’ First Amendment rights. A blog post on the San Francisco civil rights group’s website likened the subway’s move to Egypt’s decision to cut internet access to quell protests: “Bart Pulls a Mubarak in San Francisco.”

“What they did, effectively, is suppressed an enormous amount of speech that otherwise would have occurred by disabling people’s devices,” Lee Tien, an EFF staff attorney, said in a telephone interview. “They just put a cone of silence for cell phone service over the BART stations in the belief that something needed to be prevented. In my mind, that’s the electronic version for shutting down somebody.”

He added that, “I’m not aware of us having thought about actually suing yet. I’m not aware of anyone doing that.”

The American Civil Liberties Union said it was mulling legal action, but conceded that there could be instances when it would be legal for a government agency to shutter mobile-phone service.

“I don’t want to say, absolutely, that this will never be permissible,” Michael Risher, an ACLU staff attorney, said in a telephone interview. “It should not happen unless under extraordinary circumstances, real and concrete, where it is necessary to prevent some disaster.”

He does not believe that BART has met that burden. But he noted that it might be hard to put the genie back in the bottle.

“It’s very difficult to stop this from happening once,” he said. “It never happened before. There are no rules.”