The paper reviews the facts of the Gates case. Police in Bloomington, Ill., acting on a tip from an anonymous letter, obtained a warrant to search a couple's car and home after they returned from Florida and found marijuana and weapons. Applying the two-pronged Aguilar-Spinelli test, the Illinois courts concluded the warrant was not based on probable cause. The two-pronged test maintains that a warrant cannot be issued on an informant's tip unless the officers state that the reasons that led them to believe the informant are credible or that the information is reliable on this particular occasion and unless affiants state the reasons that led them to conclude that the informer obtained the knowledge in a reliable way. However, some judges and legal scholars contend that an independent police corroboration can overcome deficiencies in either or both prongs. The Court did not work out its answer under the two-pronged standard, but adopted a totality of circumstances approach, saying that the warrant is to be upheld as long as there is a 'substantial basis' for a 'fair probability' that evidence will be found in a particular case. Reasons advanced by the Court for abandoning the two-pronged test include unduly rigid application of the test by lower courts and anonymous tips that often help solve crimes but have no place in the Aguilar-Spinelli standard. The author discusses the potential impact of Gates on warrant procedures, as well as its bearing on the proposed good faith exception to the exclusionary rule. He concludes that imposing a good faith exception on top of this already diluted standard would amount to a double dilution and is neither defensible nor comprehensible. The paper includes 383 footnotes.