"That is a major safety issue," he said in his speech. "Cellphones are used to run criminal enterprises, facilitate the commission of violent crimes and thwart law enforcement."
When he was the U.S. attorney in Maryland, Rosenstein prosecuted an inmate who used a smuggled cellphone to order the murder of a witness. A gang member in North Carolina used a contraband cellphone to direct a hit on a prosecutor's father, who was subsequently kidnapped and assaulted by the inmate's associates. And an inmate in Tennessee used a smuggled cellphone to download and transmit child pornography, Justice Department officials say.
Next week, the department will begin testing a "micro-jamming" system to evaluate whether such technology can be used to halt inmates' calls without disrupting services in the surrounding area, including those used by first responders.
"There are circumstances where it is appropriate to jam cellphone signals," said Marc Rotenberg, president of the Electronic Privacy Information Center. "But these techniques are double-edged. The Federal Communications Commission has warned that cellphone jammers pose a risk to public safety."
In August, Assistant Attorney General Beth A. Williams, who leads the Justice Department's Office of Legal Policy, urged the FCC to act to stop inmates from using cellphones.
"Addressing this problem should be a chief priority" for the FCC and the Justice Department, Williams wrote. She said the cellphone problem is "significantly worse" in state and local correctional facilities.
The Bureau of Prisons — which oversees 185,000 inmates in 122 federal prisons, 11 private prisons and more than 200 community-based facilities — is also facing a safety challenge because of the increasing use of drones.
"In the old days, cellphones and other contraband items entered our facilities through the doors, or the loading docks," Rosenstein said. "In some cases, they were thrown over the fence. Today, we face another technological threat: drones that can fly contraband into jail and prison yards."
Stopping drones is difficult. "Technological solutions to detect and disrupt drones are in their infancy," Rosenstein said, adding that the Justice Department supports regulatory changes that would make it easier to deploy interdiction technology and cellphone jamming.
"Before using any technologies, we need to evaluate their compliance with a maze of federal and state laws governing the interception of electronic communications, and even laws that criminalize actions aimed at disabling aircraft," he said.
Justice officials do not know exactly how many drones are delivering cellphones, drugs and weapons to prisons in the United States or other countries.
In the summer, a drone dropped a package of cellphones, cigarettes, marijuana and razor blades inside a state prison in Michigan. In November, a drone carrying drugs and cellphones to inmates in Buckeye, Ariz., crashed in a prison yard. In 2016, London prison security cameras caught a drone delivering drugs to a prisoner's window. And two years ago, a fight broke out in an Ohio prison exercise yard after a drone dropped heroin there.
Ellen Nakashima contributed to this report.