Iris scans examine the colored tissue surrounding the eye's pupil. Unlike more invasive retinal scans, iris scans can be carried out by regular video cameras as far as two feet away from the eye. They can also be carried out on people wearing glasses.
Patented in late 1980s, iris scans' first use was to identify prisoners in a Pennsylvania prison. They have begun to be instituted to identify "the good guys" at international airports, where frequently flying passengers are allowed to use iris scanning technology to move more quickly through security checkpoints. Charlotte/Douglas International Airport in North Carolina; the Flughafen Frankfurth Airport in Germany; and London's Heathrow airport, among others, use iris scanning technology for this purpose.
Iris scanning technology is far from foolproof however. Scanners have been fooled by users placing photographs of irises over their own eyes (with holes cut out for their own pupils).
In 2005, Rep. Robert Andrews (D-NJ) introduced the Iris Security Scan Security Act of 2005, intended to give States grants to use iris scan records of convicted criminals for various purposes. On February 6, 2006, the bill was referred to the House Judiciary Subcommittee on Crime, Terrorism and Homeland Security, suggesting that the bill may be expanded to achieve homeland security or anti-terrorism objectives.