Colorado’s Supreme Court on Monday sidelined state police dogs trained to sniff for marijuana — the necessary consequence of marijuana no longer being entirely illegal, a slim majority of the court reasoned.
But, writing an unusually fiery dissent, the court’s chief justice said his colleagues may have also opened the door to deeper questions about marijuana legalization and whether it can stand against federal law.
“I object specifically to its radical reconstruction, in the wake of our recent marijuana initiative, of the state’s own constitutional Bill of Rights,” Chief Justice Nathan Coats wrote of the majority’s opinion.
Let’s jump straight into questions:
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What happened?
The state Supreme Court ruled 4-3 that a sniff of a car by police dogs trained to smell for marijuana in addition to other drugs constitutes a search — which is a big deal that doesn’t really sink in at first.
To search someone’s car, police need evidence of a crime. When the case was argued before the court late last year, lots of the talk focused on whether an alert from a pot-trained dog was enough to give police reason to dig through someone’s car looking for drugs. After all, if possession of small amounts of marijuana is now legal, how does the officer know that the dog is barking because it smells a crime?
But the majority in this case — named People v. McKnight, after a guy whose car was searched in Craig because of the bark of a police dog that was a holdover from pre-legalization days — went further. The justices said simply bringing out a pot-trained dog to sniff around now constitutes a search, in and of itself. As in, it’s something that police have to have evidence in order to do.
“The dog’s sniff arguably intrudes on a person’s reasonable expectation of privacy in lawful activity,” Justice William Hood wrote in the majority’s ruling. “If so, that intrusion must be justified by some degree of particularized suspicion of criminal activity.”
But, if police already have probable cause, they would most likely just search the car directly, themselves. Hence, this ruling almost certainly puts Colorado’s pot-trained police dogs into retirement.
BACKGROUND: Six years after marijuana legalization, Colorado still hasn’t figured out what to do with pot-sniffing dogs
So this comes down to an issue of … privacy?
Yes, and this gets to the real tension among the justices.
The majority said Amendment 64 — the recreational marijuana legalization measure — extended the privacy protections of the state’s Bill of Rights to marijuana possession, even if there’s lots of marijuana-related things in Colorado that are still illegal.
“Although possession of guns, alcohol, and tobacco can be unlawful, persons still maintain an expectation of privacy in lawfully using or consuming those items,” Hood wrote for the majority. “The same now goes for marijuana: In legalizing marijuana for adults twenty-one and older, Amendment 64 expanded the protections of (the Colorado constitution) to provide a reasonable expectation of privacy to engage in the lawful activity of possessing marijuana in Colorado.”
To the justices in the majority, this is a pretty logical conclusion.
“Our role is not to question (voters’) decision. Rather, it is to apply the logic of existing law to a changing world,” Hood wrote.
But to Coats and the two other justices in the minority, this has set a dangerous precedent with potentially far-reaching consequences.

What’s the chief justice’s deal?
Rarely in Colorado do you see a dissent so spirited. Coats calls the majority’s decision “deeply flawed” and “revisionist.”
But he also seems to be sounding an alarm about what could come from this decision. This is the money quote from his dissent:
“I am particularly concerned that in going to such lengths to craft a rationale for imposing limitations on the use of drug detection dogs, the majority unwittingly exposes not only the marijuana initiative itself but even the state’s constitutional Bill of Rights to a much greater risk of federal preemption than would previously have been the case.”
“Preemption” is the boogeyman that has hovered over Colorado’s marijuana legalization since its inception. When state and federal law are irreconcilably in conflict with one another, federal law wins and state law gets struck down. That’s what preemption means — if it comes, it’s the end of marijuana legalization in Colorado.
So far, courts have ruled that the two sets of marijuana laws can co-exist. Colorado doesn’t criminalize certain types of marijuana-related behavior under state law but it also doesn’t create an obstacle to federal agents enforcing federal marijuana law.
Coats argues that this new ruling is a step too far.
He says the majority’s opinion means that “an individual is held to have a reasonable expectation of privacy in the commission of (a) federal crime.”
The majority deals with this issue in two ways. First, they don’t go into much detail about it — because prosecutors didn’t raise preemption as an argument during the appeal. But, second, they say their ruling applies only to the Colorado constitution. They aren’t arguing that marijuana legalization gives people in Colorado a privacy protection under the U.S. constitution.
To Sam Kamin, a professor at the University of Denver who studies marijuana law, this is really significant because, he believes, it means there’s no open question about federal law. The case ends here.
“It is immunized from appeal to the United States Supreme Court,” he said.
But Coats isn’t so sure.
“While resting a decision solely on state grounds may generally be an effective technique for insulating state courts from further federal review, that is clearly not the case with regard to the supremacy of federal law,” he wrote.
And he says the majority’s ruling may even give new fuel to the preemption debate.
“I believe that after today, that question cries out for resolution more than ever before,” he wrote.

Is this really that serious?
A couple of legal experts split Monday on whether the McKnight decision represents a departure from previous rulings.
Kamin thinks not. This is just about the requirements on state law enforcement officers as they go about enforcing state law, he said.
“I don’t think this creates any obstacle to the federal government enforcing federal law,” he said. “The states are under no obligation to enforce federal law.”
But Christopher Jackson, an appellate attorney at the law firm Sherman & Howard, said there’s something different here. Previously, the Supreme Court tried to keep marijuana legalization at arm’s length.
“This absolutely could signal a very different approach that the Colorado Supreme Court will have on this issue,” he said.
There’s also an open question about what impact this will have on law enforcement. Many agencies had already retired pot-sniffing dogs or retrained them.
What’s going on behind the scenes?
Debates between Supreme Court justices are famously secretive. But, intriguingly, this is not the Colorado Supreme Court’s only pot-sniffing dog case in recent years.
There’s been two previous cases, decided in 2016 and in 2017. And both times, unlike here, the court found in favor of law enforcement. In those cases, a majority of justices said a marijuana-trained dog’s alert, when it comes in combination with other observations, is enough to justify a search.
But both of those cases also had dissents. Both dissents raised concerns about pot-trained dogs in an era of marijuana legalization, with one calling such a dog’s alert “almost meaningless under current Colorado law.”
And both dissents were written by Hood, the author of Monday’s majority ruling.
Coats and Justice Brian Boatright were in the majority in those two previous cases but switched to the minority for Monday’s ruling (joined by Justice Carlos Samour, who was not on the court for the two previous cases). Justice Richard Gabriel, who had previously joined Hood in a dissent in one of the prior cases, was with Hood’s majority on Monday.

And missing from the court was former Justice Allison Eid, who wrote the majority opinion in one of the previous pot-sniffing dog cases but was then appointed to the federal bench by President Donald Trump. Her replacement, Justice Melissa Hart, sided with Hood in the majority on Monday.
“There is, I would say, a significant shift in perspective and tone of how these cases are being approached,” Jackson said.
What happens now?
The Supreme Court threw out the evidence obtained from the search of McKnight’s car — a pipe containing methamphetamine residue — and reversed McKnight’s conviction for drug offenses.
The Colorado Attorney General’s Office, which argued that the search and the conviction should stand, has not said whether it will appeal. But with Democrat Phil Weiser taking over the office in January, it is tough to see the state pursuing a preemption argument up to the U.S. Supreme Court.
“The Attorney General’s office is studying the McKnight decision, and the office will work with its law enforcement partners in understanding this decision’s possible implications,” an office spokesman wrote in an email.
Meanwhile, we’ll just have to wait and see whether anyone picks up the red flag that the state’s chief justice just threw down and whether Coats’ dire prediction comes to pass.