If you are facing criminal charges, the police are going to build their case and gather evidence against you. It can create significant problems for that case if they have obtained any of this evidence illegally.
In some cases, this will trigger the fruit of the poisonous tree doctrine. This doctrine states that evidence obtained after an illegal action cannot be used in court. That evidence has to be omitted, even if it is pertinent to the case.
An illegal search
A common example of this is when the police want to search your home. For instance, perhaps you have been accused of illegal drug distribution, and an officer believes that you have drugs on the property.
In order to conduct the search legally, they would typically need to either get your consent or a search warrant from a judge. But if an officer does not follow the proper procedures, they could illegally enter your house and search anyway.
Say that this search does uncover illegal drugs on the premises, along with related evidence like drug paraphernalia or large amounts of cash. If the officer had gotten a search warrant first, this evidence may have clearly led to a conviction. But if they conducted an illegal search, under the fruit of the poisonous tree doctrine, all of that evidence may have to be excluded from the case.
Police procedures and your legal rights
You can see how important it is to carefully scrutinize every step the police take during an investigation. Having certain evidence omitted could have a significant impact on the outcome of the case or whether the state can even bring charges. Make sure you know what criminal defense options you have as things move forward.