As the name implies, the exclusionary rule works to exclude or “leave out” a piece of evidence in a criminal or civil trial. Essentially, this rule is used in courts across the U.S. to keep people’s constitutional rights from being abused by police or other government agents. Anyone who has watched CSI or other crime dramas on television has probably heard of the exclusionary rule, however most of these shows don’t properly depict how this rule can impact the outcome in real world cases.
Essentially, evidence that is gathered by the prosecution in an unlawful manner should be excluded from trial. When evidence is obtained in an illegal manner it may violate the constitutional rights of the defendant; if so, it cannot be used as evidence against the defendant in an effort to secure a conviction. Examples of this are when police, law enforcement agencies, or other government agencies collect evidence in an unlawful search or seizure, or other conduct that violates the defendant’s constitutional rights.
Suppose you are pulled over while driving down the road and police have no probable cause or reasonable suspicion for doing so. You weren’t speeding, driving in an erratic manner, or violating any traffic rules. All of your headlights, tail lights, and brake lights are working and your tags haven’t expired. There was absolutely no reason for police to pull you over, however in doing so they find a bag of marijuana or other illegal substance in the passenger seat. Can the bag of marijuana or drugs be used as evidence to prove the crime of drug possession? Under the exclusionary rule, it shouldn’t be admissible as evidence.