The Supreme Court is setting aside a petition from the Electronic Privacy Information Center that demanded the Department of Homeland Security release the US government's secret plan to shutter mobile phone service during disasters.

The top court, without comment, refused Monday to review a federal appeals court's May ruling that the DHS did not have to divulge the full contents of Standard Operating Procedure 303. That court held that the government could withhold the plan's contents under the Freedom of Information Act if its disclosure would "endanger" public safety.

The privacy group had demanded the document in 2011 following the shuttering of cell service in the San Francisco Bay Area subway system to quell a protest. The DHS refused to divulge the SOP 303 documents, which the appeals court described as a "unified voluntary process for the orderly shut-down and restoration of wireless services during critical emergencies such as the threat of radio-activated improvised explosive devices." (Here is a copy of a heavily redacted version (PDF) of the protocol that EPIC's lawsuit produced.)

Under the direction of the so-called National Security Telecommunications Advisory Committee, SOP 303 allows for the shutting down of wireless networks "within a localized area, such as a tunnel or bridge, and within an entire metropolitan area."

There have been no publicly disclosed instances when SOP 303 has been invoked, but the telecoms have agreed to shutter service when SOP 303 is invoked.

Local governments, however, have the power to shutter wireless service regardless of SOP 303.