A new gun-detecting machine to determine who is carrying a firearm in the subway debuted at the Fulton Center subway station in Manhattan Friday.

“To be able to detect if someone is carrying a gun and where that gun is located on that person’s body — this is good technology,” Mayor Eric Adams said. “We’re going to protect our riders.”

The technology is from a Massachusetts company called Evolv. It advertises frictionless, touchless security screening in places like sports venues and schools.

The technology already has the New York Civil Liberties Union and Legal Aid Society threatening a lawsuit. While bag checks as a counterterrorism measure are already allowed, the NYCLU believes the technology will make subway riders subjected to unconstitutional searches by the police.

“It’s very narrow to preventing a terrorist attack in the subway system,” Daniel Lambert of the NYCLU said of bag checks in the subway. “This is not that — this is a freewheeling search of individuals for firearms, possibly even for knives.”

But the NYPD’s deputy commissioner of legal matters, Michael Gerber, believes the city is on firm ground.

“We disagree. We think this is completely lawful, consistent with the case law,” he said.

The technology has also attracted scrutiny. Investors filed a lawsuit this year, accusing the company of hyping up its technology’s effectiveness, while knowing its products were ineffective at detecting weapons, like knives and certain types of firearms.

The suit also accuses Evolv of manipulating test results to make it appear its tech was more effective.

The company is under investigation by the Securities and Exchange Commission and the Federal Trade Commission for marketing practices. But Gerber said the department did its own testing and is confident in the technology.

“Can’t say it’s perfect, but we believe it is quite accurate,” he said.

The NYPD will test out one device and move it around to different stations over the next 30 days, according to a City Hall spokeswoman.

There is no contract with Evolv. It’s being tested in the subway at no cost to the city and other companies are allowed to test their tech too.

“We want them to reach out to our team because we want the best product for New Yorkers,” Adams said. “Competition is good.”

NY1 reached out to Evolv regarding its litigation and investigation. A company spokeswoman said in a statement, “We are pleased to continue to work with the NYPD as they evaluate technology as part of their overall strategy to help address violence in New York City.”