The Department of Homeland Security says it developed a portable gunshot detection system

The says its Science and Technology Directorate division has created a portable gunshot detection system with the help of a company called Shooter Detection Systems (SDS). The agency notes that whereas other systems , SDS Outdoor can pinpoint flashes of gunshots as well. DHS claims this approach can reduce false positive rates.

DHS has not disclosed details about the accuracy of the system. SDS, which is owned by , says its indoor gunshot detection system has a near-100 percent detection rate with fewer than one false alert per 5 million hours of use.

The latest system took DHS and SDS almost two years to develop, and it builds on SDS’ indoor gunshot detection tech. Prototype testing started a year ago. DHS says that law enforcement agencies who were involved in testing helped to make SDS Outdoor more effective in alerting forest responders to gunfire.

The agency claims that SDS Outdoor could be employed at temporary events in locations where infrastructure support is not typically available. It gave open-field concerts (such as festivals) and pop-up rallies as examples of situations in which SDS Outdoor could bolster security.

“Many US gunshot detection technologies are not easily deployed in the field or at temporary locations,” Dr. Dimitri Kusnezov, DHS under secretary for science and technology, . “This new system can be moved by one or two officers without the need for technicians to transport and set up. This mobile capability will help responders approach gun violence incidents with greater awareness, reducing response times and increasing responder safety.”

However, critics claim that gunshot detection systems aren’t effective enough and may cause more problems than they attempt to solve. “Past efforts to detect gunshots in real-time have not only wasted taxpayer dollars, they’ve put civilians in harm’s way when officers are falsely told that fireworks and car backfires are active shooters,” Surveillance Technology Oversight Project Executive director Albert Fox Cahn told . Fox Cahn added that there are privacy concerns around such systems, which “can often be misused as illegal wiretaps.”

Last July, the MacArthur Justice Center after police used evidence from gunshot detection system ShotSpotter in a murder case. The organization claimed that police had an overreliance on the tech and failed to follow other leads. After the suspect spent nearly a year in jail, prosecutors asked a judge to dismiss the case due to a lack of evidence.

In a study , the MacArthur Justice Center found that 89 percent of alerts that ShotSpotter sends to law enforcement has no evidence of gun-related crimes. ShotSpotter that its system had a 97 percent accuracy rate.