Biometric technologies such as voice prints, retina and iris scanners, face-recognition cameras, digitized fingerprints, and even implantable chips containing personal information can benefit us. Such technologies will find their way into cell phones and mobile computers, car doors, doorknobs, and office keys. They can bolster online commerce, locate a missing child, and transmit medical information to doctors. They promise increased security by preventing identity theft.

But no one wants to be treated like a human bar code by the authorities.

What are the benefits and concerns surrounding the further deployment of biometric identification techniques into our lives? Do they promise new levels of physical security and secure commerce–or do they threaten fundamental values of privacy and liberty? What are the distinctions between governmental, commercial, and private use of biometric technologies?

Biometrics range from completely involuntary to potentially involuntary to completely voluntary–in decreasing order of risk. The most pressing threat to liberty is an all-inclusive data-base mandated by government–a national identification card with biometric identifiers. Such an ID will increase unwelcome surveillance, will blur the distinction between public and private databases, and will undercut a presumptive right to maintain anonymity. The ID would devolve into a general law enforcement tool having nothing to do with response to terrorism.

A less sweeping biometric database would contain criminals and suspects but not the general population. Individuals would be observed, but presumably only to see if they matched a face already in the database.

Allegedly, the collection of information pertaining to criminals will have already taken place by way of proper legal procedures. Nevertheless, many observers doubt that governments can be trusted to discard incidental data collected on innocents. Because the deliberate identification and tracking of individuals using biometrics can constitute an unreasonable search, stringent Fourth Amendment safeguards are critical.

The challenge of the biometric future is to prevent mandatory national IDs, ensure Fourth Amendment protections with respect to public surveillance, and avoid the blurring of public and private databases. Private industry must generate its own information, for purposes limited by consumer choice and consumer rejection. Privacy, security, liberty, and even authentication technology itself will be all the better for it.