On the other hand, we should allow “face identification”— again, with strict rules — so the police can use facial recognition technology to identify a criminal suspect caught on camera.

With cameras so pervasive on street poles and buildings, widespread face surveillance would be Big Brother come to life, allowing for the tracking of our every movement and the stitching together of intimate portraits of our lives. Yes, banning it could cost the police the ability to nab a dangerous fugitive on the run. But allowing it could lead to the mass surveillance that China is deploying. Most Americans aren’t going to be comfortable with that, nor should they be.

Law enforcement should not have a problem with banning facial surveillance. In his essay in The Times, Commissioner O’Neill did not argue for face surveillance. And the official who heads the F.B.I.’s information services branch, Kimberly del Greco , has said, “We do not perform real-time surveillance.” The Chicago and Detroit police departments acquired the technology to conduct face surveillance, but after objections from the public, said they would not use it.

Let’s settle this now and adopt a ban on face surveillance.

On the other hand, face identification counsels a different response. Police officers face a laborious and often fruitless task when they try to match photos of crime suspects to mug shots of people who have already been arrested. Why not use facial recognition technology to assist law enforcement in this effort?

We think legislatures should allow but tightly regulate face identification. We would impose five requirements.

First, face identification should not be deployed at all until it can recognize the faces of all races and genders equally effectively. There’s enough racial bias in the criminal justice system without technology making matters worse. This can and will get solved, but until then we ought to declare a pause.

Second, face identification should be available to law enforcement only for the most serious of crimes, like murder, rape, robbery and aggravated assault. No more sniffing through motor vehicle department databases for unlawful immigrants, as I.C.E. has done, or chasing down petty criminals. The country already has overcrowded jails; too many people — disproportionately people of color — are dragged into the criminal justice system. Unless we limit the use of face identification to the most serious offenses, we will worsen this problem.