The Bay Area Rapid Transit Police Department said it cut cellphone service to aid public safety but civil liberties groups criticized the actions as a violation of free speech and argued it put people at more risk.

The Federal Communications Commission issued a public notice late Thursday seeking comment through April 30 on whether regulatory guidance is needed in these situations, and if so, what type of policies.

Last August, the BART system cut off cell service in a number of stations for about three hours during the afternoon rush hour in anticipation of protests of a fatal shooting of a man by a BART police officer.

The protesters had planned to coordinate the demonstration through their cell phones and had instructed participants to text the location of law enforcement.

"The same wireless network that police see as a tool for rioters to coordinate is the same wireless network used by peaceful protesters to exercise our fundamental freedoms," said Harold Feld, legal director for public interest group Public Knowledge.

The FCC said it would carefully deliberate before backing any framework for intentional cellphone interruptions.

"Any interruption of wireless services raises serious legal and policy issues, and must meet a very high bar," FCC Chairman Julius Genachowski said on Friday.

Among the agency's concerns is whether wireless carriers could implement a general service interruption without affecting the public's ability to make emergency 911 calls. About 70 percent of emergency calls come from cell phones, the agency said.

The FCC notice also seeks comment on the overall legality of a wireless service interruption and the FCC's authority over such shutdowns.

A coalition of public interest groups, including Public Knowledge, asked the FCC in August to immediately rule that BART violated federal law and to make clear that local government agencies could not interfere with access to cellphone networks.

But TechFreedom, a technology policy think tank that accused BART of violating the First Amendment and putting passengers at greater risk, argued on Friday that wireless service shutdowns were an issue for the courts to decide, not communications regulators.

"BART simply turned off equipment it doesn't own - a likely violation of its contractual obligations to the carriers. But BART did nothing that violated FCC rules governing network operators," the group said in a statement.

(Reporting By Jasmin Melvin; Editing by Tim Dobbyn)

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