The warrantless search of a passenger’s personal property during a traffic stop is unconstitutional, according to a ruling by the Michigan Supreme Court. The judgement overturns a 2007 decision that barred passengers from challenging similar searches by members of law enforcement.

Justices unanimously opined that the driver’s voluntary consent to allow the police to search her vehicle did not extend to the passenger’s personal belongings. They determined: “In this case, defendant had a legitimate expectation of privacy in his backpack. Defendant asserted a clear possessory interest in his backpack by clutching it in his lap, and the officer believed that the backpack belonged to defendant because of the way defendant was holding it. Therefore, although defendant had no (and claimed no) legitimate expectation of privacy in the interior of the driver’s vehicle, he had a legitimate expectation of privacy in his backpack that society is willing to recognize as reasonable.”

Justices concluded, “A passenger’s personal property is not subsumed by the vehicle that carries it for Fourth Amendment purposes.”

The defendant’s backpack held marijuana and methamphetamine. He had already served nearly three years in prison for the offenses prior to this week’s verdict.

The case is People v. Mead. A summary of the opinion is online here.