Specifically, a claim that the exclusionary rule had been broken would be barred if state courts had already given it a full and fair hearing.

[3] The arresting officer found a revolver in his jacket that turned out to be the murder weapon, and he was extradited back to California.

[5] Peak admitted being the one to plant the bomb, and would testify that the masterminds had been Rice and another NCCF member, Edward Poindexter.

It noted that "[t]he confused and confusing state of the law of search and seizure is widely recognized," and that officers had been working 18-hour days following the bombing, and ultimately judged that the hearsay evidence used (e.g. that Rice was known to be a NCCF member, that he was known to have explosives in his house) was enough support to satisfy the Fourth Amendment.

"[6] Judge Urbom then held an evidentiary hearing to assess other grounds for the search and seizure, and ultimately ruled that there were no other justifications that satisfied the Fourth Amendment.

[1][9] In an influential article Henry Friendly had noted that "the one thing almost never suggested on collateral attack is that the prisoner was innocent of the crime".

In general, the majority said, the benefits of the exclusionary rule had to weighed against its tendency to exclude "highly probative evidence.

Moreover, the physical evidence sought to be excluded is typically reliable and often the most probative information bearing on the guilt or innocence of the defendant.

As Mr. Justice Black emphasized in his dissent in Kaufman: "A claim of illegal search and seizure under the Fourth Amendment is crucially different from many other constitutional rights; ordinarily the evidence seized can in no way have been rendered untrustworthy by the means of its seizure and indeed often this evidence alone establishes beyond virtually any shadow of a doubt that the defendant is guilty."

The disparity in particular cases between the error committed by the police officer and the windfall afforded a guilty defendant by application of the rule is contrary to the idea of proportionality that is essential to the concept of justice.

[1] Brennan said it made no sense to separate the exclusionary rule from other aspects of the Fourth Amendment, and he also criticized the majority for characterizing habeas corpus laws only as judge-made laws, ignoring the fact that they had been given statutory form by Congress:[1] Under Mapp, as a matter of federal constitutional law, a state court must exclude evidence from the trial of an individual whose Fourth and Fourteenth Amendment rights were violated by a search or seizure that directly or indirectly resulted in the acquisition of that evidence.

As United States v. Calandra reaffirmed, "evidence obtained in violation of the Fourth Amendment cannot be used in a criminal proceeding against the victim of the illegal search and seizure."

White particularly complained that cases would be treated differently if they were heard on direct appeal rather than on habeas corpus petitions.

[1] However, he also expressed sympathy with the view of the majority (and Burger's concurrence) that the exclusionary rule was too often leading to guilty criminals going free, and there was too much second-guessing of police officers who were conducting searches and seizures in good faith.