Authorities in San Francisco had to shut down several city subway stations Monday after demonstrators tried to stop a train from leaving a downtown station.
The protesters were upset that the Bay Area Rapid Transit agency last week shut down cellphone access in the subway to prevent a protest.
BART police have been the target of protests over alleged brutality. Most recently, two BART officers shot Charles Hill, a transient man they said threatened them with a knife.
That shooting is one of the reasons that Jevon Cochran has come to this and other protests.
"They could have detained him in a non-lethal fashion but they chose to shoot and kill him," Cochran says.
On July 11 protester who agree with Cochran stormed a BART station and tried to stop a train from leaving. When transit authorities heard there was another protest scheduled last week, they cut off cellphone service in the subway to interfere with the organizers.
And that is what brought many of the protesters out for Monday's demonstration. Anastasia Lozano-Garcia says BART acted like authoritarian government in a country like Egypt.
"When Hosni Mubarak decided to basically flip the switch and muffle people that were out trying to turn over his regime, and this essentially what has happened here at BART when they decided to flip their switch," she says.
About a half hour into the latest demonstration, protesters once again tried to stop a train from leaving the station. But BART police cleared them out, but this time BART did not shut off cell service.
The agency faced a lot of criticism for its actions last week civil liberties groups such as the Electronic Frontier Foundation and the American Civil Liberties Union challenged BART on First Amendment grounds.
A member of the transit agency's board Lynette Sweet said it is not BART's "job to censor people."
But, Linton Johnson a spokesperson for BART defends the agency's right to act when they know cell phone service will be used to do something illegal.
"We were forced into a gut wrenching decision of how we were going to stop it given the propensity of this group to create chaos on the platform," he says.
Johnson says the group's website said they planned to break the law. So, BART authorities had to weigh rights.
"This is not a restriction on people's rights to free speech," Johnson says. "This is in fact, an enhancement of their right to safety."
Using mobile devices to organize groups of people isn't new these days. Flash mobs have used mobile devices to organize fun stuff like group dancing in a public spot. But in other cities, flash mobs have been organized to rob stores and attack people.
The question is whether cutting off cellphone service is the right way to combat the problem.