When the news gleefully announces that a bad guy has gotten off on a technicality, the technicality is usually an illegal search by the police, in other words, the Fourth Amendment to the United States Constitution, the supreme law of the United States. The Fourth Amendment prohibits “unreasonable searches and seizures,” and generally requires that the police get permission from a judge, in the form of a search warrant, before searching a private place, such as your house, your purse or briefcase, or your medical or bank records.
Whether a search is illegal only comes up if the police find evidence of a crime, so even the most flagrantly illegal search will never be discussed in any court if the police don’t actually find evidence. The evidence is usually drugs, but it could be any evidence of a crime, such as financial documents, a weapon, or whatever could be used as part of the state’s evidence in court. In theory, you might be able to sue the police for an illegal search, but because typical damages are minimal, those lawsuits are almost never worth bringing.
The primary force that stops the police from searching illegally is the consequence of the search being determined to be illegal. The evidence is thrown out of court. Judges sometimes suggest that increased professionalism or better training or something will get the police to stop searching illegally. I have never personally seen any evidence of that, and I don’t have any faith in it unless there is some consequence to individual police officers for illegal searches. And there isn’t. Police officers don’t get fired or yelled at by supervisors for illegal searches. Sheriffs don’t get voted out of office because of illegal searches by deputies, maybe because illegal searches tend to be directed against people who are less likely to vote. That’s unfortunate, but it’s the system we have. So, illegal stops, searches, and other petty harassment, against criminals and noncriminals both, is prevented by the Byzantine set of rules about when searches are legal and when they aren’t, and by enforcing those rules by excluding evidence in criminal prosecutions.
There has always been a balance between the reduced police harassment that comes from excluding more evidence and the increased convictions that come from permitting more searches. The tension apparently caused as a result is overblown, because, if illegal searches are forbidden, the police can often get a warrant and search legally. That is more hassle for the police, but that means that we aren’t balancing more illegal searches against more convictions; we’re balancing more illegal searches against the police having to do more paperwork. I’m not going to cry that the police have to go to the trouble of getting a warrant rather than harassing me unnecessarily by than searching my minivan for no reason beyond vague suspicion (or, worse, a disrespectful attitude, membership in a disfavored minority, or anti-cop bumper stickers).
The US Supreme Court sees the issue differently, and is dismantling the exclusionary rule as fast as it can. (I doubt that Supreme Court justices often get harassed by the police or worry much about the people who are.) Most recently, in Kentucky v. King , the police entered the wrong apartment, and then, because the occupants of the apartment might have flushed their drugs down the toilet after the illegal entry, searched the apartment without a warrant and found and seized the drugs. The old rule had been that, although the police could skip getting a warrant in the case of an emergency, the police could not create the emergency themselves. But the Supreme Court decided in King, 8-1 with Justice Ginsburg dissenting, that now they can create that emergency through sloppy police work, and use their own error to justify not getting a warrant. Police were sloppy enough before, when it wasn’t affirmatively encouraged by the courts.
