During protests of the World Economic Forum’s meeting in January and February 2002, New York’s Finest, on the lookout for trouble, spotted a few likely troublemakers – of the mask-wearing and pipe-sporting variety – amid ranks of peaceful protesters and took the potential rioters off the street before they could create a disturbance. As a result of the arrest of 30 potential hoodlums, thousands were able to make their views known without significant trouble. Then the police studied that protest and found ways to improve their law enforcement efforts. By our lights – and, we believe, the lights of those New Yorkers possessed of common sense – that’s a good thing. Call it Kellyism.

The left is, nonetheless, in a lather over police tactics at demonstrations, all the more so following the release, as part of a lawsuit, of several internal police department reports last week. The reports, first reported by the New York Times, are after-action analyses of the effectiveness of various methods. Among the conclusions: arresting people who obviously intend to cause mayhem reduces mayhem; the presence of police officers and vehicles seems to deter people from breaking laws; and plainclothes officers can be useful law enforcement tools.

Add it all up and what emerges is a picture of a police department doing exactly what a police department should – learning from experience to find the best way to protect the public and keep the peace. The police decided wisely against using one controversial tactic that was, according to the Times, discussed in one draft memo – namely spreading misinformation among protesters. This tactic was never executed, a spokesman for the department, Paul Browne, told us yesterday. It turns out to have been an idea in a draft that was never signed by the commander for whom it had been prepared and was never passed up the hierarchy.

The real story here is that the New York police department exercises restraint, even in the face of protesters who wouldn’t know restraint if they ran into it carrying a sign comparing President Bush to a Nazi. Mr. Browne notes that as the department prepared its strategy for crowd control at the 2002 march, the specters of Seattle, Genoa, and Montreal were in the commanders’ minds. In those cities, small bands of radicals had transmogrified larger, and largely peaceful, protests into deadly and destructive rampages. Just months after September 11, the police were keen not to let that happen in a city that was already reeling.

Meantime, those protesters have grown more sophisticated over time. Although those arrested at the W.E.F. march complain about the time it took for law enforcement to process them after they were taken in, veteran protesters have learned how to cause lengthy delays themselves to obstruct the wheels of justice. For example, Web sites advise protesters to carry lots of personal property with them to extend the time officers must spend preparing inventories of that property when it is taken from arrestees.

This is what our police department has to contend with. Back in December, the Times ran an article detailing the way in which at least one plainclothes officer had supposedly worked as an agent provocateur. Since that article and our editorial on the subject appeared, more facts have come to light. We now know that a protester “made” the officer – perhaps thanks to any of a number of fora that post pictures of officers for the benefit of protesters – and then “informed” a uniformed officer that the plainclothes man had a gun without bothering to mention that the gun-toting protester was himself an officer. That “tip” sparked a momentary arrest, and a radical succeeded in taking an officer off the street, at least temporarily.

It’s nice to know that, with protesters so pre-meditated, our police are taking the kind of savvy approach outlined in these memos. Commanders considered the stepped up presence of police transport vehicles, which some protesters viewed as a form of intimidation. They were actually meant to transport arrestees quickly from the scene, both for their safety to and prevent them from becoming a flash point for more violence. The memos show that the method was not entirely successful, as the influx of arrestees overwhelmed booking centers. So for the Republican convention in 2004, police constructed special processing facilities to move lawbreakers through the system more efficiently.

The end result is that protests as a whole are safer both for the peaceful protesters themselves and for the public. The latest memos show that the police are striving to be more effective at separating small bands of lawbreakers from the majority of law-abiding dissenters who want to make their views known. Far from hindering the exercise of free speech, the New York Police Department is enabling it by preventing large marches from degenerating into violence. If radicals in the antiwar or anti-globalization movements think that violence and destruction of property are the only ways they can communicate their message, that says more about them than about the New York Police Department.