In its everyday operations, the term “biometrics” still has a fairly simple meaning for the federal border protection workforce: It means fingerprints and photographs. The immigration and border management system used by the Department of Homeland Security – the United States Visitor and Immigrant Status Indicator Technology (US-VISIT) program – collects digital fingerprints and photographs from everyone between the ages of 14 and 79 who attempts to enter the United States, and checks these images against a database of known or suspected criminals, terrorists, and illegal immigrants.

US-VISIT is a component of – or more accurately, it is a system that will soon make use of – the largest fingerprint repository and biometric-matching system in the world, DHS’s Automated Biometric Identification System, or IDENT. By the end of 2012, according to US-VISIT Director Bob Mocny, the program will become fully integrated with this fingerprint database, enabling real-time “rapid response” capability – instead of checking against the current US-VISIT watch list of about 6 million identities, the fingerprints of incoming travelers will be checked against the DHS’ entire database of 67 million. Anyone who has ever been arrested in the United States will be flagged by the newly expanded system. While its merits may be debatable in terms of the burden it might impose on the border protection system, or in terms of the fairness of flagging arrests rather than convictions, the new US-VISIT will make it much more difficult for a person to lie his or her way into the United States at a legal entry point.

It will not make it impossible, however. Digital fingerprint scanners are not infallible – the crew of the television show Mythbusters famously tricked a door lock scanner in 2006 with nothing more than a licked photocopy of a fingerprint – and once a fraudster has obtained another person’s fingerprint, the victim will most likely never be able again to use his or her fingerprint as an ID authenticator.

A more promising, but not yet mature, biometric technology is iris recognition.  The intricate and detailed structures of the thin circular structure that controls pupil diameter are every bit as distinct as the fingerprint, and much more difficult to fake; so far, the only people to have defrauded iris scanners are fictional movie characters – either clones (Ewan McGregor in The Island) or those with gruesome schemes for acquiring the eyes of others (Tom Cruise in Minority Report; Wesley Snipes in Demolition Man). Of course, this is because the technology has not matured enough to be rolled out large-scale; there are still concerns about whether scanners will be able to accurately verify the presence of living tissue.

DHS began pilot-testing iris recognition scanners – which obtained images from subjects at distances of 3 to 4 feet, some from cameras that recorded subjects as they were walking past – at the border entry station at McAllen, Texas, some time in early 2011.  At the same facility, it has also experimented with generally less mature facial recognition technology. While results of the tests haven’t been documented, there is at least anecdotal evidence that they’ve shown promise: On Dec. 22, 2011, DHS announced that the lead contractor for US-VISIT technology, Accenture Federal Services, would be awarded a $71 contract to increase the number and types of biometric technologies used to determine the status of visitors entering the United States. The contract will include both facial and iris identification scanners, to be used on a voluntary basis by those enrolled in the program.

We’re probably not that close to having iris scanners planted at every border entry station, and the newness of the technology still makes it seem perhaps too futuristic – probably much like the video conferences between Star Trek characters used to seem before the age of Skype and FaceTime. But when biometric technologies such as iris recognition begin to impact the daily lives of Americans, the debates about the issues they present – from the intrusive iris-triggered personalized advertisements imagined in Minority Report to the real-life objections of Chris Calabrese, legislative counsel for the American Civil Liberties Union – will heat up.

“If you can identify any individual at a distance and without their knowledge,” Calabrese said, “you literally allow the physical tracking of a person anywhere there’s a camera and access to the Internet.” The argument advanced by supporters of the technology – that those who want to can simply “opt out” of a scan by closing their eyes – doesn’t hold up when you consider that systems are designed to scan subjects involuntarily, at a distance.

Still, the advantages of something as potentially failsafe as iris recognition go beyond the prevention of fraud. The technology may, someday, completely transform the experience of entering and leaving a country – perhaps rendering the passport obsolete.

Will Americans be willing to trade greater security and ease of travel for a perceived threat to privacy and civil liberty? Will they be allowed to make this choice?  Those questions will probably be answered sooner than most of us are ready to imagine.