There are rules barring the CIA from getting involved in matters of domestic surveillance. But here's some news: The CIA played a key role in developing a sketchy domestic dragnet phone snooping technology used by the Justice Department, according to a Wall Street Journal report.
Last year, we found out that there was a secret surveillance program in the US that used devices called "dirtboxes" to mimic cell phone towers. By putting dirtboxes in small airplanes, US Marshals can redirect phone traffic to hunt for suspects. In tricking phone data to redirect to dirtboxes so that law enforcement could hunt for suspects, these spy planes briefly conduct a kind of widespread data dragnet, even on people using their phones from within their homes.
They can also interfere with phone calls of whatever ordinary citizens happen to be near-ish to maybe-criminals. This is similar to Stingray spying devices used by the FBI and local police, which also screw up bystanders' cell service.
The cooperation between the CIA and the Justice Department on this technology began a decade ago, when the spy agency arranged for the Marshals Service to receive more than $1 million in gear to conduct such surveillance, said people familiar with the program.
CIA and Justice Department officials say that this close-knit, coordinated decade-long project doesn't violate rules against the CIA participating in domestic surveillance.