In Prado Navarette v. California, the U.S. Supreme Court ruled in a 5-4 decision that law enforcement officers can stop vehicles based on anonymous tips without violating the Fourth Amendment's prohibition against unreasonable searches and seizures, provided they have reasonable suspicion to believe criminal activity is taking place. The case arose from an incident where an anonymous caller reported being run off the road by a pickup truck. Police stopped the vehicle described in the tip and found large bags of marijuana inside it; however, no evidence was presented to corroborate reckless driving as initially reported by the caller. The defendants argued that this violated their Fourth Amendment rights because police did not independently corroborate illegal activity before making a traffic stop based solely on an anonymous tip. However, Justice Clarence Thomas wrote for majority opinion stating that under these circumstances "the traffic stop complied with constitutional requirements." This ruling has significant implications for privacy rights and police powers.

In the dissenting opinion for Prado Navarette v. California, Justice Scalia argued that the anonymous tip did not provide reasonable suspicion to justify a traffic stop under the Fourth Amendment. He contended that an anonymous tip alone should not be enough to establish reasonable suspicion because it does not meet the reliability standards set by previous court rulings. The police had no way of corroborating whether or not reckless driving was taking place before pulling over Navarette's vehicle as they didn't observe any illegal activity themselves. Furthermore, he criticized the majority’s decision for enabling random harassment by individuals who can simply make false reports with impunity and eroding civil liberties in favor of law enforcement convenience.