In 2005, amid reports that the London subway bombers had used cellphones as detonators, the White House secretly established the Standard Operating Procedure (SOP) 303, which granted the government the ability to unilaterally shut down all cellphone service in an area of its choosing when it feels it needs to.
The details of the procedure are still not public, and a series of lawsuits aiming to at the very least get the basics of how the law even theoretically works have faced massive official opposition, with the White House and DHS desperate to avoid any oversight.
The power has become increasingly controversial in recent years, as cellphone communication has increasingly replaced landline phones, and would be more essential than ever during “emergencies,” the very time the administration wants to be able to silence them.
An even bigger concern is that, with the details of the law a secret, officials can just flat out abuse it to silence dissent. In 2011, the Bay Area Rapid Transit system used the kill switch to shut off all cellphone services in several stations specifically to try to prevent organization of a public protest there.
The administration argues that even letting the public know the basic outline of the policy would itself be a threat to national security, and while courts have been somewhat skeptical on this claim, whenever the administration plays the terrorism card they seem to get what they want, so the safe money is on the power remaining unchecked.