Illinois v. Gates

The U.S. Supreme Court had ruled consistently in matters concerning the exclusionary rule since 1914. Again and again, it confirmed that evidence obtained outside proper legal means could not be used in a criminal trial. Yet by the early 1980s, some conservatives had argued for exceptions to this rule. President Ronald Reagan asserted that the American people had lost faith in the legal system, viewing it as constrained by constitutional loopholes and unable to protect citizens from crime. He urged the granting of greater powers to law enforcement authorities to fight crime.

The State of Illinois asked the High Court to allow the drugs seized to be presented as evidence under a "good-faith" exception to the exclusionary rule. This exception took into account that the officers had acted in "good faith" that a crime had been committed; in other words, they believed they were operating within the law. Liberals, on the other hand, argued that granting a "good-faith" exception to the exclusionary rule would invent two separate realms of the Constitution: one for citizens, who must abide by it, and another for law-enforcement authorities and the state, who were allowed to defy it. In other words, to adopt a good-faith exception to the exclusionary rule would endorse unconstitutional police behavior.