In the wake of the tragic events in Boston today, the Associated Press had earlier reported that Boston Police had ordered a shutdown of cellular service throughout swaths of the city, perhaps out of fear that additional explosive devices may be rigged to detonate using a remote trigger. Carriers have since disputed that a shutdown occurred or was ever ordered, but it raises the question: would it be legal for a police department or government agency to pull the plug?

It's clearly a tough call. Residents, Boston Marathon participants, friends, family, and officials clearly benefit from having as many communications channels open to them as possible, but there's no question that the threat of another detonation is a dire one that requires swift and decisive action.

The threat of another to detonation is a dire one that requires swift and decisive action

Intentional cellular disruptions can be legal; there's actually already a framework in place for disrupting wireless communications in the event of an emergency. The government's so-called Standard Operating Procedure 303 — sometimes referred to as SOP 303 — lays out the workflow for how agencies can request the orderly shutdown of a network. Requests go through the National Coordinating Center for Telecommunications, an agency that traces its roots to the Kennedy administration in the aftermath of the Cuban Missile Crisis, which then works with carriers for an orderly shutdown and reestablishment of service once the emergency has passed.

The problem, though, is establishing how and when Standard Operating Procedure 303 is carried out.

Had a shutdown occurred in Boston today, it wouldn't have been the first time it's happened in the United States. Northern California's BART transit system made waves in 2011 after shutting down cellular service near certain stations to prevent protests, and that incident ultimately snowballed into an FCC call for comments the following year. "Our democracy, our society, and our safety all require communications networks that are available and open. Any interruption of wireless services raises serious legal and policy issues, and must meet a very high bar," FCC chairman Julius Genachowski said at the time.

The BART incident, which sought only to quell protests, called into question the benchmark for shutting down service — and that's what led to the FCC's most recent round of discussion.

AT&T thinks SOP 303 is just fine as it is, calling the FCC's evaluation "counterproductive" in a filing. Verizon agrees that it's not an issue the Commission should be looking into: "The FCC should embrace [SOP 303] as the single nationwide process for considering and implementing a wireless network service interruption," it says.

The request for comments generated some 184 filings in total, ranging from private individuals to the very transit system that generated the controversy in the first place. BART's comments, made last year, cast a particularly long shadow in the wake of today's events:

A temporary interruption of cell phone service, under extreme circumstances where harm and destruction are imminent, is a necessary tool to protect passengers and respond to potential acts of terrorism or other acts of violence. For example, wireless devices may be used to detonate explosives. Such an explosion in a system like BART, with much of its approximately 100 miles of track located under either metropolitan downtown areas or the San Francisco Bay itself, would be devastating, not just for the passengers, but for the public at large located around the devastation or affected by flooding that could be caused by damage to the transbay tube.

It's days like today that SOP 303 — and the FCC's search for clarification on how exactly it should work — are called into focus.