In the US, the courts crafted the "suppression of evidence" doctrine as a remedy to violations of the Fourth Amendment right to be secure against unreasonable s

In the US, the courts crafted the "suppression of evidence" doctrine as a remedy to violations of the Fourth Amendment right to be secure against unreasonable searches/seizures. The courts didn't have the power to punish the law-enforcement agents who violated the Fourth Amendment (because there didn't exist an appropriate statute criminalizing the behavior or because the prosecutor was unwilling to bring charges), so instead they refused to allow such illegally gathered evidence to be presented at trial. Note that evidence gathered by a private actor (independently of any gov't investigation) is not suppressible under this doctrine.