Here's the syllabus of Justice Thomas' opinion:
A California Highway Patrol officer stopped the pickup truck occupied by petitioners because it matched the description of a vehicle that a 911 caller had recently reported as having run her off the road. As he and a second officer approached the truck, they smelled marijuana.They searched the truck’s bed, found 30 pounds of marijuana, and arrested petitioners. Petitioners moved to suppress the evidence, arguing that the traffic stop violated the Fourth Amendment. Their motion was denied, and they pleaded guilty to transporting marijuana. The California Court of Appeal affirmed, concluding that the officer had reasonable suspicion to conduct an investigative stop.
Held: The traffic stop complied with the Fourth Amendment because,under the totality of the circumstances, the officer had reasonable suspicion that the truck’s driver was intoxicated.
From Justice Scalia's dissent, joined by Ginsburg, Sotomayor, and Kagan (Note that Breyer is again ruling in favor of the government):
The Court’s opinion serves up a freedom-destroying cocktail consisting of two parts patent falsity: (1) tha tanonymous 911 reports of traffic violations are reliable so long as they correctly identify a car and its location, and
(2) that a single instance of careless or reckless driving necessarily supports a reasonable suspicion of drunkenness. All the malevolent 911 caller need do is assert a traffic violation, and the targeted car will be stopped, forcibly if necessary, by the police. If the driver turns out not to be drunk (which will almost always be the case), the caller need fear no consequences, even if 911 knows his identity. After all, he never alleged drunkenness, but merely called in a traffic violation—and on that point hisword is as good as his victim’s.
Drunken driving is a serious matter, but so is the loss ofour freedom to come and go as we please without police interference. To prevent and detect murder we do notallow searches without probable cause or targeted Terry stops without reasonable suspicion. We should not do so for drunken driving either. After today’s opinion all of us on the road, and not just drug dealers, are at risk of having our freedom of movement curtailed on suspicion of drunkenness, based upon a phone tip, true or false, of a single instance of careless driving. I respectfully dissent.