Final answer:
The exclusionary rule has a significant impact on criminal law cases, prohibiting the use of evidence obtained through illegal searches or seizures, including any further evidence derived from the initial illegality.
Step-by-step explanation:
The exclusionary rule mainly impacts criminal law cases. This rule, established by the Supreme Court in the landmark cases of Weeks v. United States and Mapp v. Ohio, dictates that evidence obtained through an illegal search or seizure without a warrant, or without falling under an exception, is inadmissible in court.
For instance, if the police conduct a search of your home without a warrant and find evidence of a crime, that evidence cannot be used against you in court. This concept also extends to the so-called "fruit of the poisonous tree," where any evidence discovered as a result of the initial illegal search is also excluded from use in court proceedings.
There are, however, several exceptions to this rule, such as the "good faith" exception where evidence is admitted if police believed they were acting according to a legally valid warrant, or the "inevitable discovery" rule, where the evidence would have been found anyway through legal means.