WASHINGTON — THE future of technological surveillance is fast approaching — and we are doing far too little to prepare ourselves.

Last week, thanks in part to documents that I and the Electronic Privacy Information Center obtained under the Freedom of Information Act, the American public learned that the Department of Homeland Security is making considerable progress on a computerized tool called the Biometric Optical Surveillance System. The system, if completed, will use video cameras to scan people in public (or will be fed images of people from other sources) and then identify individuals by their faces, presumably by cross-referencing databases of driver’s license photos, mug shots or other facial images cataloged by name.

While this sort of technology may have benefits for law enforcement (recall that the suspects in the Boston Marathon bombings were identified with help from camera footage), it also invites abuse. Imagine how easy it would be, in a society increasingly videotaped and monitored on closed-circuit television, for the authorities to identify antiwar protesters or Tea Party marchers and open dossiers on them, or for officials to track the public movements of ex-lovers or rivals. “Mission creep” often turns crime-fighting programs into instruments of abuse.

At the moment, there is little to no regulation or legal oversight of technologies like the Biometric Optical Surveillance System. We need to implement safeguards to protect our civil liberties — in particular, our expectation of some degree of anonymity in public.