The ‘Gravity Knife’ Led to Thousands of Questionable Arrests. Now It’s Legal.

Over the past 60 years, tens of thousands of black and Latino New Yorkers have been arrested for carrying so-called gravity knives — small, easy-to-access blades that are used by everyone from stagehands to steelworkers.

But on Thursday, in another demonstration of New York’s surging progressive wing’s influence, Gov. Andrew M. Cuomo ended that practice, signing a bill to remove such knives from the category of “deadly weapons,” a designation reserved for guns, daggers and switchblades, and allow their possession.

New York law defines a gravity knife as a knife with the blade in the handle that can be opened with a one‐handed flick of the wrist. They differ from switchblades, which use a spring to propel the blade into an open position automatically with the push of a button.

But critics of the old law said common folding knives and tradespeople’s knives could be deemed gravity knives if an officer was able to flick them open with centrifugal force, and some people had been arrested for possessing ordinary knives they needed for work.

In signing the bill — passed unanimously by the Democratic-led Legislature — the governor cited a March decision from the United States District Court for the Southern District of New York, which found the gravity-knife law “presents a high risk of arbitrary and discriminatory enforcement” and was “unconstitutionally vague.”

The decision was immediately hailed by public defenders and other legal advocates.

The ban and the way it was enforced constituted “one of the most discriminatory policing practices in our state,” said Tina Luongo, a lawyer with the Legal Aid Society, which issued a 2018 report showing the racial disparity in the way the law was carried out.

“For far too long, the N.Y.P.D. exploited the gravity-knife ban to drive up arrest numbers at the expense of our clients,” she said.

Gravity knives have been outlawed in New York since 1958, when the State Legislature banned a Nazi-era weapon known as “the Luftwaffe gravity knife,” according to Martin J. LaFalce, another Legal Aid lawyer.

The decision by the governor came after seven years of lobbying by lawmakers and two previous vetoes of similar legislation by Mr. Cuomo in the face of opposition from law enforcement and elected officials.

The bill’s signing on Thursday marked the latest setback for the state’s prosecutors, traditionally a powerful political force. In March, Mr. Cuomo approved legislation to create a commission to investigate prosecutorial misconduct. That commission has been challenged by the District Attorneys Association of the State of New York, which also had lobbied in the past against lifting the gravity-knife ban.

Prosecutors have also been adapting to recent changes in the state’s discovery law and its bail system, both of which were hailed as major victories by advocates for criminal justice reform, particularly in regard to treatment of minority groups.

The association held tight to its position on gravity knives on Friday.

“We continue to believe that gravity knives are dangerous weapons which do not belong in densely populated areas,” said Albany County District Attorney David Soares, the association’s president. “The governor and State Legislature have made it clear they feel differently.”

In a statement after the bill was signed, the New York Police Department said it had “opposed the legislation because gravity knives are in reality rapidly deployable combat knives.”

“There have been more than 1,600 stabbings and slashings in New York City so far this year,” the department said, adding, “The public should also be aware that the possession of gravity knives in the New York City subway system remains illegal.”

The Assembly sponsor of the gravity knife bill, Dan Quart, a Democrat from Manhattan, said that the bill signing was a clear victory over “a deep problem in the penal law” and the policies of Cyrus R. Vance Jr., the borough’s district attorney.

“It’s impossible not to look at the arrest and prosecution numbers in Manhattan, under Cy Vance, and not see a deep disproportionate racial impact,” Mr. Quart said.

A spokesman for Mr. Vance, Danny Frost, struck a conciliatory tone. “We continue to believe that gravity knives make our streets and subways less safe,” Mr. Frost said in a statement on Friday. “But we respect that state lawmakers have a different view and we are moving swiftly to implement this legislative change.”

Mr. Quart said that a gravity knife “doubles as a work tool,” and indeed, the Legal Aid Society’s 2018 report found that such knives are easily found at scores of hardware stores.

Eric Correa, a 34-year-old New York City parks department employee who was arrested on charges of possessing a knife last year, said he bought his at a uniform shop in Jamaica, Queens.

Mr. Correa said in an interview that he used it to clean his weed-whacker at work, as well as to open cans of paint. But when an officer noticed it clipped to his pants on the subway, Mr. Correa was arrested.

“It felt like maybe it was a quick collar,” said Mr. Correa, who is part Latino and part African-American. The charges against him were eventually dismissed in exchange for community service, but he lost time at work.

In previous vetoes, Mr. Cuomo had acknowledged the tension “between protecting public safety and addressing an absurd contradiction in existing commercial and enforcement practices.”

But he wrote on Thursday: “While I remain aware of the cautious community voices, I cannot veto a bill passed by the Legislature to address a decided constitutional infirmity.”

Mr. Cuomo added: “I remain confident that our law enforcement community will continue to keep our communities safe by pursuing anyone who uses, or attempts to use, one of these knives in an unlawful manner.”