The rule is not contained in the actual language of the fourth amendment. It came into existence with the 1914 decision in Weeks v. United States and became completely applicable to the States in the 1961 case of Mapp v. Ohio. Most of the limits on the rule were created or expanded by the Burger Supreme Court of the 1970's and 1980's. The Burger Court has redefined the rule's purpose as solely one of deterring police misbehavior instead of being a constitutional right of the accused. The exceptions relate to the standing of the defendant, the attenuation of derivative evidence by other evidence, the existence of an independent source of evidence, and the inevitability of discovery of the evidence. The illegally seized evidence can also be used to impeach a defendant's testimony on cross examination. Finally, the harmless error standard provides that use of tainted evidence will not result in a reversal as long as the use was harmless. The trend of case law is to exclude evidence only in cases of unreasonable police behavior or bad faith. 81 references.