ARLINGTON, Va.—Does the smell of unburnt cannabis, in a state where possession of the substance is legal, constitute probable cause for police to search someone’s car? A new amicus brief, filed by the Institute for Justice (IJ) in a case before the 7th U.S. Circuit Court of Appeals, argues the answer is “no.” 

“The simple smell of something that has a host of perfectly legal uses in a state should not be sufficient grounds for police to prolong a traffic stop and go on a fishing expedition,” said IJ Senior Attorney Paul Sherman, one of the authors of the brief.  

In June 2022, an Illinois police officer pulled over Prentiss Jackson for driving without his lights on. During the stop, the officer claimed he smelled the odor of unburnt cannabis in Jackson’s car and informed him he would search the car. At that time, Jackson opened the glove box and then removed a baggie containing two grams of unburnt cannabis, which he gave to the officer. In Illinois, possession of up to 30 grams is legal, but must be stored in an odor-proof container. (Unusually, this container requirement does not apply to hemp, which looks and smells identical to marijuana.) When the officer then ordered Jackson out of the car, Jackson dropped a gun and ran. He was then arrested and indicted under the federal felon-in-possession of a firearm statue.  

At the district court level, Jackson moved to have evidence from the stop suppressed, arguing the police had insufficient cause to search his car. But the court denied the motion, holding that the officer’s actions were justified under the state’s law requiring cannabis to be stored in odor-less containers.  

“The smell of a legal substance with innocent explanations does not give an officer probable cause to search a car,” said IJ Attorney Daniel Nelson, the lead author of the brief. “Mr. Jackson could have been handling cannabis before he entered his car, he could have been carrying the smell of cannabis from a house or dispensary, or his car could have contained legal hemp. So, the officer needed some other facts suggesting the smell in that particular instance indicated illegality before he could lawfully search the car.”  

Nelson added, “Vigorous judicial enforcement of probable cause is particularly important in the context of automobile searches, which are typically conducted without a warrant issued by a neutral judge. Instead, police on the scene get to decide whether they have probable cause for a search. And because of abusive practices like civil forfeiture—which allows police departments to seize and keep cash and other property merely suspected of being involved in a crime—those officers often have strong financial incentives to search, regardless of whether probable cause really exists. If judges don’t closely review those decisions, drivers are left with no protection from abusive searches.”  

Through its Project on the Fourth Amendment, IJ defends the rights of Americans to be secure in their persons and properties against unreasonable searches and seizures. Following IJ’s lawsuit, an Iowa court recently declared an Orange City, Iowa law that required warrantless inspections of all rental properties unconstitutional. IJ is currently suing game wardens in Virginia after they snuck onto a family’s private property and stole cameras. IJ is also arguing before the Michigan Supreme Court that towns should not conduct warrantless drone surveillance to look for code violations.