When is the exclusionary rule inapplicable?

The purpose of the exclusionary rule is to prevent the government from wrongfully obtaining evidence against a criminal defendant and then presenting that evidence during a criminal trial in order to convict them. It attempts to prevent the government from pursuing a Machiavellian "The ends justify the means" approach to justice. However, outside this specific circumstance, the exclusionary rule doesn't force the government to pretend as if it never saw the evidence. With that in mind, let's walk through the situations that sometimes get tested where the exclusionary rule is not applicable:

(1) Grand Juries are not the same as Trial Juries. The purpose of a grand jury is to decide whether or not there is enough evidence to justify indicting a defendant and proceeding with a trial. In other words, it is possible for a grand jury to hear evidence that would be barred from a criminal trial.

(2) Civil proceedings aren't criminal proceedings, so the exclusionary rule is inapplicable.

(3) There are times where a search may be inappropriate or shady, but ultimately does not violate the law or the Constitution. In such cases, though the police may be jerks, the exclusionary rule doesn't apply.

(4) "Parole" occurs when a prisoner is released before the completion of their sentence in exchange for them obeying various restrictions. It is an agreement where the government says, "Hey, you've been found guilty and we have every right to keep you to the full extent of your sentence. However, if you're willing to abide by some strict rules, we'll let you out now." In other words, parolee's generally have less rights than normal citizens. Thus, if evidence is wrongfully obtained that shows the parolee should have their parole revoked, the exclusionary rule does not prevent the evidence from being considered.

(5) "Impeachment" is the act of calling into question the integrity or validity of something. The exclusionary rule may prevent some wrongfully obtained evidence from being admitted in order to convict someone of a crime, but it won't stop the evidence from being used for the narrow purpose of impeachment.

(6) If police genuinely and sincerely—in good faith that they are acting lawfully—obtain evidence, then that evidence is admissible even if it was—in reality—obtained illegally. A common example of this is if an officer executes a warrant they believe to be valid but, unbeknownst to them, is not.

(7) Generally speaking, there are rules police must follow when executing a warrant. One of which is the need to knock and announce themselves. If they forget to do so, this isn't enough to undermine the validity of the warrant being executed.