The US Supreme Court on Tuesday narrowed the permissible scope of warrantless automobile searches. In a 5-4 decision the high court upheld a 2007 Arizona Supreme Court ruling that cited the 1969 California v. Chimel US Supreme Court case to conclude that police had to obtain a warrant before searching a car in the absence of any threat to officer safety or ability of the suspect to destroy evidence (view Arizona opinion). The Arizona ruling went against nationwide trend diminishing the protections against unwarranted searches.

"Lower court decisions seem now to treat the ability to search a vehicle incident to the arrest of a recent occupant as a police entitlement rather than as an exception justified by the twin rationales of Chimel," Justice John Paul Stevens wrote for the majority, citing former Justice Sandra Day O'Connor.

The case at hand spent nearly a decade going back and forth through the Arizona courts. It began on August 25, 1999 when two Tuscon police officers received a "tip" that drug activity took place at a certain location. Police went there and questioned Rodney Gant who happened to open the door of the house that was under suspicion. After leaving, the officers looked up Gant's record and found that there was an outstanding warrant for his arrest for driving under a suspended license.

The officers waited for Gant to return to the house and arrested him after he parked his car safely in the driveway. Gant was placed in the back of a squad car within minutes and without incident. Police then proceeded to search Gant's car where they found a small plastic bag containing cocaine.

A majority lead by Justice Stevens found the search of Gant's car unconstitutional.

"The state seriously undervalues the privacy interests at stake," Stevens wrote. "Although we have recognized that a motorist's privacy interest in his vehicle is less substantial than in his home, the former interest is nevertheless important and deserving of constitutional protection. A rule that gives police the power to conduct such a search whenever an individual is caught committing a traffic offense, when there is no basis for believing evidence of the offense might be found in the vehicle, creates a serious and recurring threat to the privacy of countless individuals. Indeed, the character of that threat implicates the central concern underlying the Fourth Amendment -- the concern about giving police officers unbridled discretion to rummage at will among a person's private effects."

The high court did leave police with a broad prospect for conducting warrantless searches but closed the door to searches based solely on traffic violations.

"Although it does not follow from Chimel, we also conclude that circumstances unique to the vehicle context justify a search incident to a lawful arrest when it is reasonable to believe evidence relevant to the crime of arrest might be found in the vehicle," Stevens wrote. "In many cases, as when a recent occupant is arrested for a traffic violation, there will be no reasonable basis to believe the vehicle contains relevant evidence."

Less than a day after the decision was released, the Michigan State Police issued guidance to officers on how to get around the supreme court's new limitations.

"While this ruling will impact how searches of vehicles incident to arrest are conducted, officers may still conduct a full search of a person incident to a lawful arrest," the state police bulletin explained. "In addition, officers may search vehicles using other exceptions to the warrant requirement (e.g. probable cause, inventory, consent)."

A copy of the decision is available in a 260k PDF file at the source link below.