The fourth amendment was drafted to preserve the preexisting common law right of people to be secure in their persons, houses, papers, and effects against unreasonable searches and seizures. The common law, however, did not protect illegitimate expectations of privacy, such as a criminal's desire to maintain possession of contraband, nor did it prohibit lawful intrusions by government officers. The Supreme Court articulated and applied these common law principles in several important search-and-seizure decisions, ruling that a seizing party acted at his peril, was liable for damages if he turned out to be mistaken, and that probable cause did not constitute a valid defense. The Court also held that any issues which arose as to the validity of the original seizure were irrelevant to the government's case. Congress frequently modified the common law rule of strict liablity for fruitless seizures. The exclusionary rule immunizing fruitless seizures based on reasonable doubt or probable cause was first applied in cases involving searches considered illegal at common law, but later was extended to search considered legal under common law, such as successful searches of vehicles for contraband. Although the Court never justified this expansion, the theory appears to be that common law was not an effective deterrent to minor police misconduct. In most exclusionary rule cases, events have proven the officer's suspicions to be correct, and the court has had to decide whether it was unreasonable and irrational for the officer to have entertained suspicions which proved to be accurate. Thus, suppression motions alleging the lack of reasonable cause are almost always denied, and the inquiry seems pointless. In addition, police officers who engage in fruitless searches risk personal liability under both case and statutory law unless they can demonstrate reasonable cause for suspicion. While the new rules adopted in the 1960's did suppress egregarious police searches, they also resulted in criminals being freed on technical or inadvertent police errors and courts being swamped with meritless suppression motions. The paper includes 168 footnotes.