Know three things, and you will not fall into sin—a seeing eye, a hearing ear, and all thy deeds written in a Book - The Talmud, Avot 2:1

Recently Attorney General Grewal ordered New Jersey police departments not to use facial recognition (FR) software developed by a company called Clearview AI. What distinguishes Clearview's product from other FR software is that its database isn't limited to images in law enforcement and other public records. Instead, Clearview has been systematically collecting pictures from the entire online universe of social media and other websites. As a result, individuals who are not otherwise "known to the police," to use the English expression, can now be identified by Clearview, at least tentatively, for further investigation. There is an open issue whether Clearview had the legal right to record these images for its purposes or whether they amount to fruit of a poisonous tree. There is another, akin to fingerprints and DNA evidence, as to whether and how far the state should collect identifying information about individuals who are not suspected of any violation of the law.

The concern with FR technology is real and understandable. In the first place, it has been criticized as inaccurate, especially with images of people of color and women, creating false positives and false negatives. But it is likely that those defects will be worked out by further research and more complete databases, because the demand for a fully accurate product exists. The real issue with FR technology is not that it doesn't work but that it does, or soon will. When combined with the increasingly pervasive use of video surveillance by governments, businesses and even homeowners with video doorbells, it raises the specter of a public sphere in which any individual's location and movements can be tracked and pinpointed at any time. Reporting indicates that the Chinese government is trying to use the technology to its fullest potential as part of its comprehensive "social credit" system to track and measure the reputation of every individual.

We are far from that point in this country, but anxiety about FR is part of the general gestalt in which our purchases, our interests, and our whereabouts are tracked, recorded, sold, and used to sell. It may be flattering when the maître d' at our favorite restaurant knows what we like.  It is more disconcerting when the internet knows, and much more disconcerting if the government were to know.

Traditional Fourth Amendment law is of little use in response because it does not address what is seen and done in public. The Fourth Amendment and its New Jersey counterpart protect the individual against physical detention. They also protect her "houses, papers and effects," which is to say spaces and information over which she has ownership or control, against government intrusion. However, they have not been held to prohibit the state from collecting openly available information about an individual. On the contrary, the plain view doctrine has long held that the state can gather and use information that its agents see, hear or smell in a place where they have a right to be. And the public street is just that—public—which means that the state and its agents have the right to be there. Nothing in the Fourth Amendment has ever prohibited the government from deciding that someone is of interest, opening a dossier, and having them followed by its agents in public, as long as no trespass or intrusion is involved.

What FR technology threatens is not privacy as the law knows it, but rather privacy's cousin obscurity, which is the ability to go about our affairs unnoticed, unrecognized and unremembered in the crowd. Obscurity is the product not so much of law as of the limits of resources. In the late 19th century, urban police would hold regular identification parades, where detectives would come to gaze upon and commit to memory the features of recently arrested criminals. There were mug books in every police station and "wanted" posters cluttering every post office. But human memory is limited, as is the number of policemen with the skill to follow in public undetected. The combination of pervasive video recording and FR software is a change of degree so great as to amount to a change of kind. Technology is moving in the direction of a universal eyewitness in public space, who sees all and remembers all.

We reject the idea that the way to keep ourselves safe from the state is to keep it in ignorance. Action uninformed is more dangerous than action based on fact. We therefore see no issue with collecting the most comprehensive image database from lawfully available sources. We see no reason why a person who has committed a crime in public view should be able to remain in obscurity.

The issue with the FR-video combination, as with any other source of information, is what use the state is permitted to make of it, and under what conditions. In the enforcement of the criminal law, how reliable should an FR positive be regarded? Is it admissible evidence of guilt?  Is it probable cause sufficient to support an arrest or a search warrant? Is it the articulable suspicion needed for a street stop? Is it at least a rational investigatory lead that can prompt further inquiry? These are questions that the law is used to asking. The foundation and reliability of fingerprints, of DNA, of the breathalyzer, of the drug sniffing dog and of assorted laboratory tests has been and regularly is questioned, both in general and as the technique is applied in the particular case. If that means examining the source code of FR software, that is no different than the scrutiny applied to the breathalyzer. If it means limiting the probative force of an FR identification, that is no different than the limits placed on eyewitnesses reviewing photo spreads or lineups. As long as FR evidence is critically scrutinized in the judicial process, it can be placed under appropriate limits based on data and experience.

The more troubling issue is the use of FR and other identifying technology outside criminal prosecution. It is part of the substantive question of when and why the government should be able to keep a file of information about an individual's actions, movements, habits, or preferences. In our age of readily available and searchable personal information, Amazon and YouTube may know what you like, but they can't close your business or send you to jail for it. The state can and does, as many pedophiles could testify. If there are going to be limits on the government's power to collect, store and correlate publicly available information about individuals simply because it might prove useful some day, they will have to be legislated.