The wireless service in BART’s underground stations is provided by Sprint, Verizon, AT&T and T-Mobile [GALLO/GETTY]

A rail transit provider in the United States disabled mobile phone services to prevent a planned protest on Thursday, attracting criticism and unflattering comparisons to crackdowns on dissent in the Middle East.

Demonstrators in northern California’s Bay Area had planned a protest to condemn the shooting death of Charles Hill, who was killed on July 3 after Bay Area Rapid Transit (BART) police officers responded to complaints about a drunk man at a station in the city of San Francisco.

Hill was fatally shot in the torso – police said he had lunged with a knife – and protesters responded eight days later with a demonstration that shut down three San Francisco BART stations.

BART’s police force had been criticised before, in 2009, after a white officer responding with several colleagues to a complaint restrained an unarmed black man on the ground of a train platform and then fatally shot him in the back. That shooting also prompted protests, and the officer served less than two years in prison after being convicted of involuntary manslaughter.

In a statement released on Friday, BART said organisers planned another protest over the Charles Hill shooting during busy commute times on Thursday, which “could lead to platform overcrowding and unsafe conditions”.

“Organisers planning to disrupt BART service on [Thursday] stated they would use mobile devices to co-ordinate their disruptive activities and communicate about the location and number of BART police,” the statement said.

“BART asked wireless providers to temporarily interrupt service at select BART stations as one of many tactics to ensure the safety of everyone on the platform.”

James Allison, the deputy chief communications officer for BART, told Cnet News that mobile services were disabled in four San Francisco stations from 4pm to 7pm local time.

But BART offered varying explanations, probably with different legal ramifications, for how the shutdown had actually occurred.

In its first statement, BART said it had asked mobile service providers to stop their service. Then, a BART deputy police chief told the local online news outlet SF Appeal that BART turned off the services itself, as it is allowed to do under its contracts with the providers – Sprint, Verizon, AT&T and T-Mobile. About the same time, BART changed its official statement – which was posted on its website – to say that “BART temporarily interrupted service”.

Unflattering comparisons

The mobile phone disruption comes at a sensitive time: Regimes in the Middle East have in the past eight months used far harsher Internet and mobile phone blackouts to squelch dissent, and David Cameron, the British prime minister, suggested this week that he would examine ways to hamper the use of social media to prevent civil disturbances and riots like those that brought violence and looting to London and other cities over the past week.

The online hacker group Anonymous launched a campaign, OpBART, to overwhelm the transit agency with faxes and emails, and critics on Twitter began relaying news of the communications shutdown using the hashtag #muBARTek, a play on the last name of deposed Egyptian President Hosni Mubarak.

On Thursday, BART police Lieutenant Andy Alkire told the local Bay City News agency that while it was unusual to block mobile services, it was “a great tool to utilise for this specific purpose”.

Linton Johnson, BART’s spokesman, told the local KTVU television channel that BART “didn’t try to shut down the protest. They simply turned off the cell service so it couldn’t become viral.

“It really is just a cost-benefit analysis of where your freedom of speech begins to threaten the public safety.”

Blackout a legal uncertainty

Federal law makes jamming mobile phones illegal in the United States, but the situation in San Francisco was not clear cut, and it appeared that BART did not use jamming technology.

Mobile signals do not normally reach underground BART stations, so when BART shut down the technology that made those signals available, it argued that it was simply eliminating a complimentary service.

That makes the legal situation murkier. Sprint, Verizon, AT&T and T-Mobile provide mobiel service to underground BART station, and those companies have a legal obligation to provide services as part of being granted their federal licenses to operate, but if BART turned off the service itself, where does the responsibility lie?

“This may well affect the legality of BART’s actions … but it doesn’t affect the impact,” said David Wagner, a computer science professor at the University of California – Berkeley who has written about wireless communications security. “In this day and age, deliberately disrupting cellphone service is dangerous to public safety, no matter how it is done.”

Jesse Choper, a professor at the Berkeley School of Law and a constitutional law expert, said BART could argue it had acted to preserve public safety rather than halt a protest but that blocking mobile services to entire areas may have obstructed more free speech than was necessary.

The US Supreme Court has never dealt with a case such as the BART communication shutdown, Choper said, but in the past has issued opinions that lay out how authorities may prevent protests.

Any move to block a demonstration must satisfy four basic criteria, he said. It must be neutral on the content of the demonstration, serve a significant government interest, leave open an alternative venue, and be narrowly tailored to avoid restricting more free speech than is necessary, he said.

If he were arguing in BART’s defence, Choper said, he would say that the broad mobile phone blackout had not discriminated based on the content of the protest, that it served the significant interest of protecting public safety, and that protesters could still have demonstrated elsewhere, such as forming a picket line outside the stations.

But it could be argued, Choper said, that the service shut down had obstructed more communications than needed.

“The question is, what less should they have done,” he said. “Would you want them to monitor every call?”