Jillian Snider, a retired New York police officer who now teaches at John Jay College of Criminal Justice, said neither the Mamdani plan nor the City Council proposal outlines how a 911 dispatcher should handle such calls, which can come in with little information about the circumstances.

“When someone calls 911 and says, ‘Help, help, I’m having a crisis” then click, how is that person trained to say is this a safe situation,” Ms. Snider said. “Is this person a danger to themselves or others?”

She said it would be safer and more effective to invest more in programs that pair officers and mental health professionals so they can respond together, an approach that has been tried in other parts of the country, including in New Jersey.

“I don’t think the default should be not to send cops,” Ms. Snider said. “That situation can get extremely dangerous very quickly.”