By Amanda Merkwae
In June, the Wisconsin Supreme Court ruled that police have a right to search a person after a traffic stop if they believe the vehicle smells like cannabis, reversing a lower court’s decision that the odor of marijuana cannot be the sole basis on which a search is conducted.
Under the law, police need “probable cause” to search a person’s clothes or body. They must have concrete evidence that leads them to believe the person is probably engaged in some sort of criminal activity. Conducting a search without probable cause is illegal.
In 2022, both a circuit court and an appeals court found that the scent of cannabis alone doesn’t constitute probable cause to search, reasoning in part that the odor of illegal cannabis is indistinguishable from the smell of perfectly legal CBD. But the state Supreme Court declared that it does justify a search. This is bad news for our civil liberties. These searches don’t require a warrant or the gathering of any other evidence of a crime being committed — all police need is to smell what they 
think is weed.
Allowing police to search someone simply because they believe they smell cannabis is misguided and could lead to wrongful searches and false arrests. As the dissenting justices note, cannabis can smell identical to other legal substances, so it’s impossible to determine with any meaningful certainty whether cannabis is actually present solely on the basis of odor. An officer, using scent as their only guide, cannot possibly differentiate clearly between cannabis and other legal hemp-based products, since they smell exactly the same.
Another dangerous aspect of the plain smell test, as it’s been called, is that it’s unverifiable. There is no way to prove whether an officer truly smelled cannabis or not, and there is no reliable way to authenticate or challenge that assertion. This means police could use the smell of cannabis as a pretext to conduct searches, lawful or not, knowing that their justifications cannot be scrutinized. We have seen this result in inappropriate searches already, and it is partly why the Wisconsin Supreme Court’s affirmation of this doctrine is so concerning.
Anyone who cares about racial justice must also recognize the racially disparate way in which searches are conducted. Black and Latinx drivers are far more likely to be searched than white motorists, even though contraband is found at comparable rates. We also know Black people in Milwaukee are far more likely to be stopped and frisked by police, while Black Wisconsinites are four times as likely to be arrested for cannabis possession compared to a white person. Given what we know about how laws are enforced in Wisconsin and across the United States, we can reasonably expect Black and Brown people to be disproportionately targeted by these searches.
A search should never rest solely on the smell of cannabis. It leaves too much room for mistakes, wrongful searches, police misconduct and racially biased law enforcement. Wisconsin should do as several other states have done and change the law to prevent citizens from being searched exclusively because their car smells like cannabis.
Amanda Merkwae is the Advocacy Director of the Wisconsin ACLU. This piece was originally published in The Capital Times on July 1.
