The exclusionary rule is a legal principle in U.S. constitutional law that prevents the use of evidence acquired through breaches of a defendant’s constitutional rights, mainly under the Fourth Amendment. Based on safeguards against illegal searches and seizures, it acts as a safeguard against government overreach and ensures adherence to due process. Legal scholars and judges, such as William Jennings Bryan, who doubted its constitutional foundation, and Justice William J.
Brennan, who highlighted its importance in maintaining constitutional protections, have discussed its reach and effectiveness. The rule’s development, from early cases like Weeks v. United States to the pivotal Mapp v. Ohio, illustrates its contested application in reconciling justice with procedural rights. Its constraints, such as exceptions in civil matters and the "fruit of the poisonous tree" doctrine, emphasize its intricate role in influencing judicial responsibility.