Although rumors persist of their use in restaurants and movie theaters, the use of cell phone jamming equipment remains illegal in the US. Right now, the only permissible use is by federal law enforcement officials, but that may change if state prison officials in South Carolina and a manufacturer of jamming equipment have their way. Both would like to see state law enforcement get permission to use the jammers, which may push the technology a bit closer to the mainstream.

Jammers are relatively simple, as they simply rely on flooding the frequencies that cell phones use with electromagnetic noise, blocking any effective transmission within a limited radius. Right now, the FCC is responsible for enforcing the ban on devices that block signals from cell phones, an authority that dates back to the Communications Act of 1934. The FCC notes that "the Act prohibits any person from willfully or maliciously interfering with the radio communications of any station licensed or authorized under the Act or operated by the US government." First time offenders may face either fines of up to $11,000 or a year in prison for each violation.

You can imagine how many offenses jamming something like a crowded movie theater might involve. Nevertheless, it's widely reported that the FCC has yet to actually hold someone accountable for doing so, and it's also widely reported that distributors have shipped the equipment to do so here from overseas; see, for example, this story in Slate.

There are obvious public safety concerns surrounding the unrestricted use of these jammers; it's hard to imagine that blocking access to 911 is in anyone's best interest, but there are situations where public security can be enhanced by their use. Although it hasn't been a problem in the States, cell phones have been used as remote detonators in terrorist attacks.

In other cases, cell phones have apparently been smuggled into prisons, where they have enabled inmates to continue to organize crimes on the outside or to further coordinate the smuggling in of goods. For such reasons, federal law enforcement agencies have retained the right to deploy these systems, and have apparently done so at federal prisons.

The new push seeks to broaden the use of jammers by enabling their use at the state level. Following a demonstration of the equipment at a South Carolina state prison, the company that supplied the demonstration equipment (CellAntenna, which primarily sells signal extenders) has indicated it would attempt to get a waiver from the FCC that would give states permission to use them. Meanwhile, the demonstration has caught the attention of at least two US senators, who may in turn nudge the FCC along.

The development isn't interesting so much for the fact that states might get access to something the federal government is already using; those sorts of things happen all the time. What makes it intriguing is the fact that technologies designed for law enforcement have shown a consistent ability to escape their confines in recent years. It's easy to visit web sites that now offer a variety of stun guns and pepper sprays for sale to the public. There's no guarantee that cell phone jammers will go this route, but any changes that increase their use certainly make it more likely.