In Arizona v. Gant, 556 U.S. 332 (2009), the Supreme Court ruled that a motor vehicle may be searched incident to the arrest of a recent occupant “only if  the arrestee is within reaching distance of the passenger compartment at the time of the search or  it is reasonable to believe the vehicle contains evidence of the offense of arrest.” The second justification for a vehicle search under Gant was new, and the Court stated with little explanation that it was based on “circumstances unique to the vehicle context.” But just how far does search authority under that exception extend?
First Gant exception limited to passenger compartment. As a preliminary matter, a vehicle search incident to arrest that is based on the arrestee’s proximity to the vehicle is pretty clearly limited to the passenger compartment. The Gant opinion refers to the arrestee being “within reaching distance of the passenger compartment.” Furthermore, such a search is justified because of the risk that the arrestee could grab a weapon or destructible evidence. That risk is substantial with respect to the passenger compartment of a vehicle, which is normally quickly accessible from the outside. The risk is less with respect to the trunk, which is typically inaccessible from the outside.
Analyzing the second Gant exception. But what about a vehicle search incident to arrest that is based on reason to believe that evidence of the offense of arrest is in the vehicle? For example, if an officer arrests a vehicle occupant for a drug offense, the officer might reasonably believe that the vehicle contains additional evidence of drug activity. Such evidence could as easily be in the trunk as in the passenger compartment. May the officer search the trunk of the vehicle?
Probably not, though I don’t think the issue is completely settled. In the portion of the Gant opinion dealing with the second exception, the Court states that “in [certain cases], the offense of arrest will supply a basis for searching the passenger compartment of an arrestee’s vehicle and any containers therein.” Of course, saying that an officer may search the passenger compartment isn’t quite the same thing as saying that an officer may not search the trunk. But the reference to the passenger compartment is consistent with the pre-Gant understanding that vehicle searches incident to arrest were limited to the passenger compartment, not the trunk. And among cases to have considered the issue, a majority have ruled that the second Gant exception does not support a search of the trunk. See Robinson v. State, 754 S.E.2d 862 (S.C. 2014) (suggesting in a footnote that Gant did not extend the permissible scope of a search incident to arrest beyond the passenger compartment of a vehicle; applying Gant’s “reasonable to believe prong” and finding that a trunk “would normally be excluded from the permissible scope of the search [incident to arrest],” but that the trunk search at issue was permissible because the particular trunk was freely accessible from the backseat); People v. Coates, 266 P.3d 397 (Colo. 2011) (concluding that Gant did not “expand the applicability of the search-incident-to-arrest doctrine in the vehicle context to include areas beyond the passenger compartment of the vehicle”); Smith v. Kenny, 678 F. Supp. 2d 1124 (D.N.M. 2009) (though not essential to the holding, the court noted in a post-Gant case that “a search incident to an arrest would not allow the officers to search the car’s trunk”). But see State v. Stewart, 807 N.W.2d 15 (Wis. Ct. App. 2011) (relying on Gant’s “reasonable to believe” prong, the court found with little discussion that a search of a trunk was a valid search incident to arrest where defendant was lawfully under arrest for cocaine possession). I can imagine an argument that the second Gant exception should not be limited to the passenger compartment because evidence may be found in the trunk, and because the trunk shares a reduced expectation of privacy with the rest of the vehicle. But the state of the law is such that an argument along those lines would face an uphill battle.
Other justifications for trunk searches. As a practical matter, when there is “reason to believe” that the vehicle contains evidence of crime, there will often also be probable cause that the vehicle contains evidence of a crime. And when there is probable cause, the entire vehicle, including the trunk, may be searched without a warrant under the vehicle exception to the warrant requirement. Other justifications for a warrantless search of the trunk, in appropriate cases, include consent and an inventory search.
Back to the Court? I imagine that the Court will clarify the second Gant exception at some point. It created the exception out of whole cloth and offered little explanation of its justification or scope. A case involving a trunk search incident to arrest would be a prime fact pattern for the Court to consider.