A desire to unplug and live in the moment isn’t the only reason you should consider powering down these days: IMSI catcher devices — otherwise known as StingRays or cell site simulators — could be tracking your phone without your permission or knowledge. These portable surveillance tools work by sending out a signal that mimics a cell phone tower, tricking your phone into joining a fake network. From there, the gadget can collect locational data from your device. At best, StingRays enable law enforcement agents to track down and arrest bad guys. At worst, they are a serious violation of federal communications laws as well as the right to privacy. StingRays and other devices like them send signals into both public and private spaces to glean information about phones within the search zone — and even when police are trying to track a particular suspect’s phone, the private information of bystanders is easily accessible, says Nathan Freed Wessler, staff attorney at the ACLU’s Project on Speech, Privacy and Technology. "These devices operate totally surreptitiously. The average person would have no idea if their phone had been swept up by a fake tower operated by police." What’s more: The New York Times reports that when police departments purchase StingRays, officers are required to sign a nondisclosure agreement prohibiting discussion of the technology with the public. That means that citizens might not even know if they live somewhere where police departments utilize the so-called “cell tower spoofers.” They also might not know if their tax dollars were used to procure the tech in the first place. While departments might be able to snag a StingRay using federal grant money, the devices can still cost up to $170,000 each. “We should know what our tax dollars are spent on,” says Wessler, “and police can’t get out of that by signing on the dotted line.” This is how extreme secrecy — like not being able to discuss the fact that these devices are being employed — becomes a tool of impunity, he goes on. “It allows police to engage in invasive surveillance.” This all raises questions around what law enforcement agencies are doing with the data they obtain, as well as how long they hold on to it. Police often don’t apply for warrants to use the devices, according to Wessler, and that stands in direct violation of the fourth amendment. So, while the close tracking capabilities may prove a boon to law enforcement agencies, legislators are wary: One bill filed in Washington state moved to ban StingRays without a warrant, while a second would prohibit state agencies from providing material support or resources to the NSA. According to the ACLU’s current estimates, 48 agencies across 20 states and the District of Columbia own StingRays, but because these devices fly below the radar and are used in secret, the organization suggests the numbers are higher. More than 90% of Americans own cell phones these days; thus far only one app on the market, called SnoopSnitch, alerts users to this type of surveillance. Currently, it's only available for Android phones. “We should not have to choose between participating in modern life and using cell phones and losing our privacy rights. When the government engages in this kind of tracking without proper oversight, it puts us in a real bind,” says Wessler. And, until tracking devices come out of the woodwork, it will be a hard one to get out of.