With other nations already utilizing such technology, the U.S. Homeland Security Department is preparing to test biometric devices that will let it track passengers when they exit the country, in response to a congressional mandate that it has struggled for more than a decade to fulfill.

Congress first called for an automated system to track when foreign nationals exit the country in 1996, so authorities can know who overstays their visas.

But the logistics of implementing a system to collect biometrics at every exit point from every person flying or driving out of the country has proven too complicated and costly a task for DHS so far.

At a conference held by the National Institute of Standards and Technology earlier this month, Arun Vemury, a program manager from the DHS Science and Technology Directorate, provided an overview of the technologies that Customs and Border Protection might use at airports to collect biometrics from passengers exiting the country.

One option is a device installed at every airport gate where passengers would scan their fingerprints before they can pass through onto the jet bridge. Scans could also occur at a centralized location that passengers would pass through in order to access the wing of the terminal where their gate is located.

Alternatively, CBP or airline personnel might use mobile equipment that they can bring to gates to collect fingerprints or iris scans. Another option would be facial recognition software connected to a video camera on the jet bridge that identifies all the passengers boarding a plane. […]