US President Barack Obama, surrounded by US Secret Service agents, walks to greet guests after arriving on Air Force One at Griffiss International Airport in Rome, New York on May 22, 2014. Obama is traveling to visit the National Baseball Hall of Fame and Museum in Cooperstown, New York, before attending Democratic fundraisers in Chicago. AFP PHOTO / Saul LOEB (Photo credit should read SAUL LOEB/AFP/Getty Images)

WASHINGTON (AP) — A new policy allows the Secret Service to use intrusive cellphone-tracking technology without a warrant if there’s believed to be a nonspecific threat to the president or another protected person.

Homeland Security Assistant Secretary Seth M. Stodder described to a House subcommittee Wednesday the department’s policy on the use of cell-site simulators.

Civil libertarians and privacy advocates have long expressed concern about the suitcase-size devices, known as Stingrays, which mimic cell-towers to scoop up electronic data that can be used to locate nearby phones and identify their owners. The devices don’t listen in to phone calls or capture text messages, Stodder said.

The policy the department unveiled this week is similar to the one announced in September by the Justice Department, which includes the FBI.

Federal law enforcement officers are required to get a warrant signed by a judge before using Stingrays, except under emergency “exigent circumstances” meeting the constitutional standard for probable cause under the Fourth Amendment, but when there is no time to get a warrant.

Stodder cited the example of kidnappings, such as a recent case where Immigration and Customs Enforcement officers used a Stingray to help locate and rescue a 6-year-old girl being held hostage by human smugglers in Arizona.

But Stodder said another allowed exception under the policy would let the Secret Service use Stingrays in “exceptional circumstances” without meeting the legal threshold for probable cause. In such cases, using the devices would require direct approval from “executive-level personnel” at Secret Service headquarters and the U.S. attorney for the relevant jurisdiction.

Asked whether that essentially granted a blanket exception for the Secret Service, Stodder said that the exemption would not be used in routine criminal probes, such as a counterfeiting investigation.

“The key exception that we envision is the Secret Service’s protective mission,” Stodder said. “In certain circumstances where you could have an immediate threat to the president and you have cryptic information, our conclusion in drawing the line between security and privacy here is to err on the side of protection.”

Stodder added that such information could be “a cryptic email or something like that” indicating a security threat to the president where agents would lack the time or the information to determine probable cause, “but you need to locate that person.”

Cell-site stimulators have been used for years by both state and federal law enforcement agencies, who tout them as a vital tool to catch fugitives and locate suspects. But privacy groups and some lawmakers have raised alarms about the secrecy surrounding its use and the collection of cellphone information of innocent bystanders who happen to be in a particular neighborhood or location.

Stodder could not immediately say how many times department law-enforcement officers had used Stingrays without warrants in recent years.

Rep. Ted Lieu, D-Calif., said Wednesday the newly announced guidelines are a good first step, but added that the policy still lacks transparency and provides overly broad permission for Stingrays to be used without warrants. The new federal policies also don’t apply to state and local law enforcement agencies that have purchased Stingrays, sometimes through the use of federal grants.