Federal Communications Chariman Julius Genachowski applauded the Bay Area Rapid Transit (BART) board of directors decision to codify when it was appropriate to block cellphone use in its stations.

The board, which drew criticism over summer when it decided to block cellphone signals to avoid a potential protest, ruled that it would turn off wireless communications only in the face of a “extraordinary circumstances.”

Such circumstances include evidence that cellphones are being used as “instrumentalities in explosives,”,to facilitate criminal activity such as the taking of hostages, or to facilitate plans that would destroy property or “substantially disrupt public transit services.”

In those circumstances, the board decided, it could institute a “narrowly tailored interruption of service.”

Genachowski said that BART had taken an “important step” in responding to the concerns raised by its actions over the summer but that the FCC will be reviewing the issue of when it’s appropriate to disrupt cell service.

“For interruption of communications service to be permissible or advisable, it must clear a high substantive and procedural bar,” he said.