Today a federal judge ruled that the New York Police Department's "stop and frisk" program violates both the Fourth and 14th amendments. Responding to a class action lawsuit by black and Hispanic targets of the NYPD's street stops, U.S. District Judge Shira Scheindlin concluded that police commonly detain, question, and pat down New Yorkers without the "reasonable suspicion" the Supreme Court has said the Fourth Amendment requires. She also found, based on data showing who is stopped and what happens afterward, that cops decide who is suspicious based partly on race, thereby violating the 14th Amendment's Equal Protection Clause.

Scheindlin's analysis of data on 4.4 million stops made between January 2004 and June 2012 strongly suggests that reasonable suspicion is the exception rather than the rule. During this period, she notes, only 12 percent of people subjected to the "demeaning and humiliating" experience of being treated like a criminal were arrested or issued a summons. Even more striking, although police are supposed to frisk a subject only if they reasonably believe he is armed, 52 percent of these encounters included pat-downs, only 1.5 percent of which discovered a weapon. Even when officers reached into subjects' clothing after feeling what they thought was a weapon, they were right only 9 percent of the time.

The officially recorded justifications for stops provide further evidence that New York cops' suspicions are frequently less than reasonable. "Between 2004 and 2009," Scheindlin notes, "the percentage of stops where the officer failed to state a specific suspected crime rose from 1% to 36%." Since stops are always supposed to be based on a reasonable suspicion of criminal activity and cops are free to prevaricate, unchallenged, on the forms they fill out, the fact that they fail to even name the crime they claim to have suspected more than a third of the time suggests a pretty casual attitude toward the Fourth Amendment. The reasons they offer for suspecting someone was up to no good are similarly vague. Two of the most popular are "high crime area" and "furtive movements." Regarding the latter excuse, Scheindlin observes:

Two officers testified to their understanding of the term "furtive movements." One explained that "furtive movement is a very broad concept," and could include a person "changing direction," "walking in a certain way," "[a]cting a little suspicious," "making a movement that is not regular," being "very fidgety," "going in and out of his pocket," "going in and out of a location," "looking back and forth constantly," "looking over their shoulder," "adjusting their hip or their belt," "moving in and out of a car too quickly," "[t]urning a part of their body away from you," "[g]rabbing at a certain pocket or something at their waist," "getting a little nervous, maybe shaking," and "stutter[ing]." Another officer explained that "usually" a furtive movement is someone "hanging out in front of [a] building, sitting on the benches or something like that" and then making a "quick movement," such as "bending down and quickly standing back up," "going inside the lobby… and then quickly coming back out," or "all of a sudden becom[ing] very nervous, very aware." If officers believe that the behavior described above constitutes furtive movement that justifies a stop, then it is no surprise that stops so rarely produce evidence of criminal activity.

The fact that people stopped by police turn out to be innocent nine times out of 10 figures in Scheindlin's equal protection analysis. Mayor Michael Bloomberg and NYPD officials say the vast majority of people stopped by the cops (83 percent during the period Scheindlin considered) are black or Hispanic because the vast majority of criminal suspects are black or Hispanic. Bloomberg, in fact, argues that the crime statistics justify an even greater racial disparity, saying cops should be stopping fewer white people and more people with darker skin, even though the numbers indicate that the reasons for stopping blacks and Hispanics already are flimsier than the reasons for stopping whites, who are more likely to be caught with weapons or other contraband. Scheindlin does not buy Bloomberg's argument:

The City and its highest officials believe that blacks and Hispanics should be stopped at the same rate as their proportion of the local criminal suspect population. But this reasoning is flawed because the stopped population is overwhelmingly innocent—not criminal….While a person's race may be important if it fits the description of a particular crime suspect, it is impermissible to subject all members of a racially defined group to heightened police enforcement because some members of that group are criminals. The Equal Protection Clause does not permit race-based suspicion.

Scheindlin rejects another argument Bloomberg uses to defend the stop-and-frisk program:

One NYPD official has even suggested that it is permissible to stop racially defined groups just to instill fear in them that they are subject to being stopped at any time for any reason—in the hope that this fear will deter them from carrying guns in the streets. The goal of deterring crime is laudable, but this method of doing so is unconstitutional.

Bloomberg himself has offered a similar rationale, likening street stops to DUI checkpoints, which aim to deter drunk driving rather than catch drunk drivers. Accordingly, the mayor says, the fact that guns are found during a tiny and shrinking percentage of stops shows the program is working. This argument abandons any pretense that the program is constitutional, since the Supreme Court has approved random stops of motorists at DUI checkpoints under a special traffic safety rationale that does not apply to the NYPD's stops of pedestrians, which are supposed to be based on individualized suspicion.

The result-oriented approach that Bloomberg takes is inherently hostile to civil liberties, which by design make law enforcement more difficult. "This case is not about the effectiveness of stop and frisk in deterring or combating crime," Scheindlin writes. "This Court's mandate is solely to judge the constitutionality of police behavior, not its effectiveness as a law enforcement tool. Many police practices may be useful for fighting crime—preventive detention or coerced confessions, for example—but because they are unconstitutional they cannot be used, no matter how effective." Police and their boosters tend to lose sight of this distinction, which is why we need judges like Scheindlin to enforce it.

You can read Scheindlin's ruling here. Her remedies, which include an independent monitor, are described here.