That which can keep people out, can also keep people in.

DHS seeks cutting-edge biometric solutions for border screening | Biometric Update

DHS has outlined ambitious performance goals for the technologies it wants to see. Systems must be able to detect and collect biometric data from travelers who are standing, walking, or inside vehicles. They must also match captured data against both trusted-traveler databases and federal watchlists of criminals, immigration violators, and terrorism suspects.