Given the data, Scheindlin had little choice but to find that the stop-and-frisk policy violated the Fourth Amendment as well as the equal protection clause of the 14th Amendment. A large number of searches have been conducted without reasonable suspicion, and these suspicionless searches have disproportionately targeted racial minorities. Of 19 individual stops, the court found that nine of the stop-and-frisks were unconstitutional, five of the frisks after stops were unconstitutional, and five were constitutionally permissible.
As MSNBC’s Adam Serwer notes, particularly telling is that most defenses of the NYPD’s program all but conceded its unconstitutionality. Rather than trying to deny that the program was discriminatory, defenders instead tried to change the subject to the question of whether it was effective. This response is defective for two reasons. First of all, effectiveness is not in itself an adequate defense of an unconstitutional policy. Scheindlin makes this clear: “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.”
Even if one were to argue the effectiveness of the policy should cause us to overlook those pesky Fourth and Fourteenth Amendments, the evidence for the NYPD program’s effectiveness is very weak. The argument rests on a post hoc ergo propter hoc fallacy—violent crimes rates have dropped in New York, New York has a discriminatory stop-and-frisk program, so the declining crime rates must have been produced by the discriminatory stop-and-frisk program.
There’s no reason to make this causal inference. The drop in violent crime rates in New York began well before the current stop-and-frisk program. Violent crime is declining nationally, not just in New York. Violent crime continued to drop in New York in 2012 even as the number of stop-and-frisk searches declined.
More at the link.