You get arrested when the police enter your home and find a bag of illegal drugs in your bedroom. They consider it an open-and-shut case. The drugs were obviously at your house, you were there at the time, your fingerprints are on the case where the bag was found and all of the drugs are illegal under both state and federal law.
But the problem is that the police entered your home without a warrant and without your consent. Can they still use this evidence that clearly shows that you committed a crime?
Evidence obtained unlawfully would be inadmissible in court
The fact of the matter is that illegally obtained evidence is inadmissible in court and cannot be used to prove your guilt, even if all parties involved (even you) know that the evidence does, in fact, prove your guilt. The police violated your rights and broke search and seizure laws to get that evidence, so they have to exclude it from the case. If they have nothing else, they cannot continue with the charges.
What this demonstrates is that it’s not just what the police know that matters, but also how and why they know it. In this hypothetical example, they know full well that they had reason to arrest you, but they didn’t have legal standing to uncover that fact, so they can’t use it against you. This law is in place to protect people from random searches or other types of illegal searches.
As such, when you’re facing charges, it is important to understand even the finer points of the law and to know exactly what procedures are supposed to be followed.