Recently there have been calls for the NYPD to cut down on street stops, sometimes known as “stop, question and frisk” — a tactic that has been a part of policing since time immemorial.

As far back as 1911, the state Legislature passed the Sullivan Law, with its seven-year sentence for individuals who carried a gun without a license — and cops began routinely searching persons who appeared to be carrying a firearm. In other states, field interrogations were always a common police tactic.

The US Supreme Court upheld the practice in 1968; the key question in individual cases is whether the search is “reasonable.” In determining that, appellate courts will often disagree by margins of 3-2 or 5-4. But a police officer faced with the prospect of being shot can’t engage in a leisurely deliberation.

During the crime deluge of the 1960s, ’70s and ’80s, New York cops had less time to conduct field interrogations because they were spending as much as 90 percent of their tours of duty answering 911 calls. The NYPD was reduced to containing crime rather than significantly reducing it. By 1990 the city was recording over 2,000 murders a year, up from about 500 in the mid ’60s.

Then the NYPD commenced a huge rollback of crime, employing intensive patrolling and enforcement in high-violence areas. In this model, police don’t wait for someone to call 911 after a crime occurs; they instead try to stop criminals before they can strike. These police interventions sometimes cause people to complain.

In the wake of the Colorado mass shooting, there will be calls for stricter law enforcement against guns. Yet when police take action they are criticized. For example, the fact that relatively few guns are recovered in New York street stops is cited as negating the need for searches. Actually, that fact indicates that gun-carrying has declined significantly because criminals fear they may be searched.

New York’s efforts have been so successful that our overall crime rate is now 75 percent lower than it was 20 years ago. Murders are back down to the 500-a-year level.

The story’s different elsewhere. If we look at murder (a crime that is very accurately reported), our rate per 100,000 population is now about a fourth as high as Chicago’s, and a fifth of Philadelphia’s. If we had Philly’s rate, we’d be in the range of 2,000 murders this year — back to the bad old days.

Some argue that the NYPD should adopt “community policing,” a concept that’s been touted for nearly 40 years but has never been shown to have much effect on the crime rate.

Chicago has maintained an extensive community policing program for years, yet homicides there are going through the roof. Gang members who go around shooting up neighborhoods don’t listen to community leaders who implore them not to engage in violence. Nor do gang-bangers and characters like the Colorado shooter turn in their weapons at the local police station when a gun-buyback is announced.

New Yorkers today have to choose between retaining proactive policing, which has kept the city safe for so long, or going back to the reactive model that was in effect when the streets of many neighborhoods were dominated by criminals.

In deciding, keep in mind the fate of Detroit. Not too long ago, it was one of America’s top five cities. Then violence began to tear it apart. Its murder rate is now 10 times higher than New York’s — and Detroit has seen two thirds of its population flee.

Back in 1990, New York looked to be heading that way, with national publications featuring stories about the fall of the Big Apple. It didn’t happen because New Yorkers fought back effectively.

New York’s current policing model (like any program) can always be improved. But calls to virtually abolish it must be resisted, lest we return to the bad old days when gunmen ruled the streets and crime threatened to destroy the greatest city in the world.

Thomas A. Reppetto is the former president of the Citizens Crime Commission of New York City; his next book is “American Police, 1945-2012: