Weighing in on an international debate about censorship and public safety, BART proposed Wednesday to limit cellphone service blackouts to "extraordinary" circumstances threatening train service or public safety.

The Bay Area Rapid Transit District board will consider the policy -- the first of its kind by a public transit agency in this nation -- at its meeting 9 a.m. Oct. 27 in Oakland.

The policy is a response to criticism against BART after the agency turned off cellphone service Aug. 11 in four underground stations in San Francisco to thwart communications among police critics trying to organize a protest.

BART officials said they were protecting public safety against a protest that was aimed at disrupting service and could have stranded passengers in stopped trains. Critics compared the action to that of authoritarian governments trying to crush dissent.

Under the proposed policy, BART could interrupt cellphone service only if there is "strong evidence of imminent unlawful activity" that threatens to harm passengers, employees, transit property or cause substantial disruption of train service.

Examples of "extraordinary circumstances" include threats that cellphones would be used to detonate explosions or in hostage taking plots, BART officials said.