Yesterday I was interviewed for an NBC Boston story about DHS funded research to build a machine that would enable the electronic searching of hundreds of people at a time. The system would work sort of like the all electronic tolling gantries on the Massachusetts Turnpike, which, equipped with various types of cameras and sensors, clock every car as they pass under the metal scaffolds. But this technology wouldn’t be scanning cars, it’d be scanning people—and potentially in the process violating their Fourth Amendment rights.

There are a lot of problems with tech like this, even apart from the fact that the government using it on a public street would likely violate the Constitution.  

First, there’s no guarantee that the technology will work. Take the naked scanners at airports, for example. We were told these machines would be a security improvement over metal detectors. But they weren’t. In fact, they were “shit,” according to a former TSA employee. Writes Politico: “Officers discovered that the machines were good at detecting just about everything besides cleverly hidden explosives and guns.” Despite its failures, the technology was useful for at least one person: former DHS Secretary Michael Chertoff, whose consulting group reportedly scored big when TSA made the switch to the scanners—which were manufactured by his client.

Second, even if the technology produced some valuable “hits” on the street, the risk of false positives is quite serious and likely outweighs the technology’s benefits. In an interview with NBC News, one of the researchers working on the street scanning system at Northeastern University couldn’t answer the journalist’s question about false positives. But the false positive rate really matters with technology like this.

Just imagine that you’re walking into a Red Sox game where one of these machines has been installed. There’s an alert, and suddenly men with guns swarm the crowd, yelling for everyone to get down on the ground. Someone nearby you is hauled from the crowd and rushed out. That person may have had a gun or a bomb on them. Or they may have simply forgotten to take scissors out of their purse before heading to the game. If that person is a white woman, they may be handcuffed, questioned, and let go. If that person is a Muslim man or a Black person, they may be roughed up or worse. 

Overall, it seems like this technology—like a lot of ‘security’ tech—is driven by a desire to search for an answer to problem that doesn’t really exist. Is it really so bad to wait in a security line before entering a ball game or a concert? The small annoyance of having to wait in line to go through a metal detector is preferable, in my view, to the danger of creeping warrantless spying, and of the false positives that will inevitably result from the use of tech like this on the streets or at security checkpoints—false positives that could result in much more serious civil liberties violations, especially for people of color and people perceived to be Muslim.