On Thursday, BART's Board of Directors agreed to wait at least two weeks before deciding on the guidelines that would spell out when it could block cellphone service.
The board members want more time to refine the wording on the policy.
Board members do agree that the agency should only shut down service for an extraordinary event.
"It has to be real clear that it's a terrorist attack, that it's a potential life-threatening situation," said BART director Lynette Sweet. "It has to be something that we know could lose a life."
BART agreed to develop the policy after facing intense criticism for shutting down service on August 11. BART officials say they were trying to ensure public safety, but critics say it was an attempt to stop a planned anti-police protest.