More than 50 years have passed since the Supreme Court decided the Weeks case, barring the use in federal prosecutions of evidence obtained in violation of the Fourth Amendment, and the Silverthorne case, invoking what has come to be known as the "fruit of the poisonous tree" doctrine. The justices who decided those cases would, I think, be quite surprised to learn that some day the value of the exclusionary rule would be measured by-and the very life of the rule might depend on-an empirical evaluation of its efficacy in deterring police misconduct. These justices were engaged in a less ambitious venture, albeit a most important one. They were interpreting the Fourth Amendment as best they could. As they saw it, the rule-now known as the federal exclusionary rule-rested on "a principled basis rather than an empirical proposition." The dissenters in United States v. Calandra were, I think, plainly right when they maintained that "uppermost in the minds of the framers of the [exclusionary] rule" was not "the rule's possible deterrent effect," but "the twin goals of enabling the judiciary to avoid the taint of partnership in official lawlessness and of assuring the people [that] the government would not profit from its lawless behavior, thus minimizing the risk of seriously undermining popular trust in government.'' The main purpose of this article, then, is to trace, explain and justify the original grounding of the exclusionary rule-what has come to be known as "the imperative of judicial intergrity. "
Kamisar, Yale. "Is the Exclusionary Rule an 'Illogical' or 'Unnatural' Interpretation of the Fourth Amendment?" Judicature 62 (1978): 66-84.