367 U.S. 643 (1961), that the exclusionary rule was held to be binding on the states through the doctrine of selective incorporation.) Subsequently, the defense in many criminal trials attempted to prove that a search warrant was invalid, thus making the search illegal and hence the evidence obtained through the search inadmissible in the trial. However, there were no hard guidelines defining the legality of a search warrant and it could be difficult for a judge to decide upon a warrant’s validity. In order to obtain a search warrant in the United States, a law officer must appear before a judge or magistrate and swear or affirm that they have probable cause to believe that a crime has been committed. The officer is required to present their evidence and an affidavit to a magistrate, setting forth the evidence. "An affidavit must provide the magistrate with a substantial basis for determining the existence of probable cause." In other words, the law officer must present evidence, not merely their conclusions. "Sufficient information must be presented to the magistrate to allow that official to determine probable cause; his action cannot be a mere ratification of the bare conclusions of others." In Johnson v. United States, 333 U.S. 10 (1948), the Court said: Development of the two-pronged test In Aguilar v. Texas, 378 U.S. 108 (1964), the Court said: In Spinelli v. United States, 393 U.S. 410 (1969), the Court went further by requiring that a magistrate must be informed of the "underlying circumstances from which the informant had concluded" that a crime had been committed. Abandonment of the two-pronged test In Illinois v. Gates, 462 U.S. 213 (1983), the Supreme Court explicitly abandoned the two-pronged rule in favor of the totality of the circumstances rule. According to the opinion, written by Justice William Rehnquist: Survival of the two-pronged test in state law Individual states can provide more rights under their own laws than the Federal Constitution requires. At least six states — Alaska, Hawaii, Massachusetts, New York, Vermont and Washington — have rejected the Gates rationale and have retained the two-prong Aguilar–Spinelli test on independent state law grounds. State law references References