The police in Bloomington, Ill., received an anonymous tip in May 1978 of an alleged prospective drug buy in Florida. What they did and what the courts thought of it may produce one of the most important reviews of federal court procedure in 68 years.
Acting on the tip, Bloomington police got a search warrant and seized from the couple's home and car 350 pounds of what was alleged to be drugs, weapons, and ammunition.
But Illinois courts threw out the evidence under the ''exclusionary rule'' instituted by the Supreme Court in 1914 and broadened in 1961. This says in effect that evidence obtained improperly can't be used to decide criminal cases - it must be thrown out: excluded. The Illinois courts ruled the police had violated the Fourth Amendment prohibition of ''unreasonable searches and seizures,'' and that evidence obtained from following the tip was tainted and inadmissible.
That threw the matter right into the middle of a continuing dispute: Is American justice hobbled by technicalities? What makes interest intense in the present case, Illinois v. Gates, is growing pressure to modify the exclusionary rule to allow evidence to be admitted if the police acted in ''good faith'' and believed they had obtained it legally.
The Reagan administration has floated the idea of creating a ''good faith exception'' to the rule. That alarms some people.
''(The proposed change) would encourage police to be ignorant of the law and result in illegal searches of innocent persons,'' says David Landau, staff counsel of the American Civil Liberties Union.
Interest in the issue has been building for some time:
* Chief Justice Warren Burger told the 1981 convention of the American Bar Association, ''Crime and the fear of crime have permeated the fabric of American life.''
He declared: ''We have established a system of criminal justice that provides more protection, more safeguards, more guarantees for those accused of crime than any other nation in all history. . . . Are we not hostages within the borders of our own self-styled enlightened, civilized country? . . . (Rather than slogans to reduce crime), a far greater factor is the deterrent effect of swift and certain consequences: swift arrest, prompt trial, certain penalty, and , at some point, finality of judgment.''
* The Reagan administration has been emphasizing the crime issue. Modification of the exclusionary rule is a major feature of the crime package the President recently sent Congress. US Attorney General William French Smith asked Congress to pass a ''good faith exemption'' to the exclusionary rule relaxing its effect. The federal Fifth Circuit Court of Appeals adopted the exemption two years ago. Mr. Smith argued that his proposal ''would avoid the release of criminals when an officer commits at most a technical violation.''
The court made its new approach known in a one-paragraph, unsigned order that set the Bloomington case for reargument. Originally questions about the exclusionary rule itself were not raised in the case. Later the state asked permission to broaden the case to include the rule, but the high court unanimously rejected the appeal. Now the court majority has reversed signals and asked the lawyers to prepare to debate the question of modifying the rule.
The action was so unusual that three associate justices filed an opinion of dissent: John Paul Stevens, joined by William J. Brennan and Thurgood Marshall.
The exclusionary rule was a reaction to illegal searches and to brutal procedures by law enforcement activities. These extorted confessions from suspects.
A task force of the American Bar Association last year opposed changes in the exclusionary rule. There appear to be differences within the Supreme Court itself. The sudden shift of position on hearing the case may signify that Chief Justice Burger believes he's lined up five of the nine justices in favor of altering the exclusionary rule. Only last June, in an Alabama case, the court declared it would not adopt an exception to the controversial rule.
Speaking for the minority, Justice Stevens called the majority's decision ''a flagrant departure'' from ''settled practice'' that ''raises serious questions.'' The new order, he wrote, ''sheds a distressing light on the court's conception of the scope of its powers.''
The Philadelphia Bar Association, in testimony by Alan Ellis Dec. 2 before a House judiciary subcommittee, opposed congressional efforts to modify the exclusionary rule.
''In our view, such efforts are unconstitutional, unwarranted, and unnecessary. The desire to adopt such 'easy' solutions to the nation's serious crime problem will only result in abandonment of constitutional protections - but with very few additional criminals ending up behind bars.''