A report from researchers at the Center on Privacy and Technology at Georgetown University's law school say a new biometric exit tracking system being implemented at US airports by the Department of Homeland Security is too invasive.In the report, the Georgetown University team say the system is an un-needed surveillance tool that the department has installed at nearly a dozen airports without going through a required federal rule-making process.”It's telling that D.H.S. cannot identify a single benefit actually resulting from airport face scans at the departure gate,” said Harrison Rudolph, an associate at the center and one of the report's co-authors, told the New York Times.”D.H.S. doesn't need a face-scanning system to catch travelers without a photo on file. It's alarming that D.H.S. still hasn't supplied evidence for the necessity of this $1 billion program,” he added.Acting Customs and Border Commissioner Kevin McAleenan told a Senate panel in November that biometric exit technology could be installed in airports nationwide within four years.Currently, CBP has the technology on trial at single departure gates at Hartsfield-Jackson Atlanta International Airport, Washington Dulles International Airport, Houston George Bush Intercontinental Airport, Chicago O'Hare International Airport, Las Vegas McCarran International Airport, Houston William P. Hobby Airport and John F. Kennedy International Airport.A biometric exit capability allowing CBP to track visa holders leaving the county has been a protracted challenge for the agency.