This is the largest area of application of biometric technologies, and the most direct lineage to the feudal gate keeping system. Initially mainly used in military and other "high security" territories, physical access control by biometric technology is spreading into a much wider field of application. Biometric access control technologies are already being used in schools, supermarkets, hospitals and commercial centres, where the are used to manage the flow of personnel.
Biometric technologies are also used to control access to political territory, as in immigration (airports, Mexico-USA border crossing). In this case, they can be coupled with camera surveillance systems and artificial intelligence in order to identify potential suspects at unmanned border crossings. Examples of such uses in remote video inspection systems can be found at
A gate keeping system for airports relying on digital fingerprint and hand geometry is described at
An electronic reconstruction of feudal gate keeping capable of singling out high-risk travellers from the rest is already applied at various border crossing points in the USA. "All enrolees are compared against national lookout databases on a daily basis to ensure that individuals remain low risk". As a side benefit, the economy of time generated by the inspection system has meant that "drug seizures ... have increased since Inspectors are able to spend more time evaluating higher risk vehicles".
However, biometric access control can not only prevent people from gaining access on to a territory or building, they can also prevent them from getting out of buildings, as in the
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