Incriminating evidence that is obtained illegally should be allowed in court. For instance if an illegal wiretap proves guilt than (a) use it to convict the guilty party and (b) go ahead and process whoever is guilty of executing the illegal wiretap.
The flaw in our justice system is that we essentially destroy the factual evidence, which itself is incapable of doing anything right or wrong: it is merely a fact to be considered. Pretending it doesn't exist is "willful ignorance"(aka "stupidity").
Closing this loophole would also help convict more KNOWN felons.