Jonah, the no-knock ruling in Hudson v. Michigan is a good one. I think because these kinds of decisions are always rhetorically portrayed as “the police versus the individual,” we have a tendency to see the cops as if they were independent actors. The police (especially when they have a valid warrant issued by an independent judge based on probable cause) are the agents of the public. It is the public – not the police – whose laws are at issue, whose peace is breached by crime, and who have a right to presentation in court of evidence that the law has been violated.
When the exclusionary rule is invoked, it is not the police who are penalized. It is the public. Yes, it is a given when we are in the “exclusionary rule” context context that an official wrong has been committed. The question is what remedy is most in the public interest to address the wrong.
The exclusionary rule punishes not the police officer who has violated a rule, but the public. When evidence is suppressed by the exclusionary rule, the public is deprived of the use of evidence of guilt when it tries to promote public order and safety by depriving a criminal of his liberty. The criminal, moreover, gets a windfall. His possession of the evidence of his crimes is wholly unrelated to whatever wrong has been committed by the police officer. (The cocaine is in his closet whether the cop knocks or not.)
If a non-criminal’s home is lawlessly invaded by a police officer, he has to content himself with suing the police for trespass – he does not get, in addition, a free pass to commit a future crime. Why should a criminal, on top of being able to sue, get the added bonus of suppression of damning evidence? What is the public interest in that?
This is not to say that police misbehavior should be forgiven or encouraged. It is simply to say that there are other effective mechanisms for that (suing the police, firing or suspending the cop, prosecuting the cop if the misconduct is serious enough, etc.). Certainly, you can argue that some police violations are so serious it is worth punishing the public in order to discourage future violations. I would not agree with that, but I would concede it is a very viable argument. However, whatever violations may belong in this category of very serious violations, a failure to knock plainly is not one of them. (Keep in mind, for years courts have been able to waive the requirement and issue “no knock” warrants in cases where police make a showing that knocking may put them in danger. One of your correspondents talks about the militarization of the police; in point of fact, many criminal gangs are better armed and far more ruthless.)