Hey, stoners. Put the bong down for a minute. I’ve got something you might be interested in.

I heard a story last week from some folks coming from Colorado to camp in southern Utah. Along Interstate 70, there was one of those electric road signs warning police were ahead and on the lookout for people transporting drugs.

Officers conducting that operation were from the Western Colorado Drug Task Force, but I found out it’s a tactic the Utah Highway Patrol has also been using for some time.

And, it turns out, it’s ingenious and a bit devious, too.

Here’s why: We’re all aware of drunk driver checkpoints. Law enforcement puts them up, usually around holidays — often near bars — and conducts random stops and sobriety checks.

Casting that kind of net almost always snares a lot of fish — drunk fish, I suppose — and the courts have ruled that, in the interest of keeping roads safe, those kinds of checkpoints are legal given some constraints (they have to be limited in time, they have to be publicized in advance and the cars stopped have to be random, things like that).

But in 2000, the U.S. Supreme Court ruled in the case of Indianapolis v. Edmond that drug checkpoints are different. Because people who might have drugs weren’t immediately endangering other drivers, and because finding those drugs would require a police search, the court ruled 6-3 that blanket drug checkpoints were unconstitutional.

So why are the Utah Highway Patrol and the Colorado task force — and law enforcement in many other states — still doing them?

They aren’t … technically.

What they’re doing is called a “ruse checkpoint.” The Utah Highway Patrol, for example, will post a sign that says something like “K-9 Drug Unit Ahead.” And that’s true. There is a drug-sniffing dog up the road.

There are also troopers, sometimes a dozen or more, watching for drivers who suddenly decide it’s a good idea to make a quick U-turn, or they have officers staking out the exit just past the sign watching for people who pull off and toss a baggie in the trash or chuck something out of the window.

The illegal U-turn gives officers all the reason they need to pull over a driver, says Sgt. Nick Street, spokesman for the Utah Highway Patrol. Troopers can’t legally detain a driver longer than they need to conduct the traffic stop, but while one officer is checking the license and registration, another can walk around the car with a dog.

And if you’ve ever seen those dogs work, you know they are really, really good at their job.

Boom! Enjoy jail.

“It’s a ruse,” Street said. “I hate to use the word ‘deceitful.’ But you’re not going to get stopped [at random]. And it’s truthful.”

Maybe it’s not deceitful. It definitely feels shady. But, you know, smuggling narcotics is more than shady. It’s a crime.

In the highway patrol’s last operation, troopers found a load of heroin stashed behind a gas cap and the driver was charged with distribution. They also made two DUI arrests and caught a handful of additional drug offenses.

That recent Colorado decoy operation nabbed a handful as well, including one driver with 36 pounds of marijuana and another with nearly 33 pounds of methamphetamine.

Clearly, the ruse checkpoints tiptoe around the Fourth Amendment protection against unreasonable search and seizures, and in some instances courts in other states have ruled police have crossed that line.

For example, the courts have ruled that, just because a driver took an exit after a drug checkpoint sign, it didn’t create enough suspicion to justify a stop or search. That was even the case in a Missouri checkpoint where a driver swerved dramatically to avoid missing an exit after a ruse checkpoint sign.

The ruse has to be set up to focus on likely traffickers, while weeding out as many innocent people as possible — the suspicion has to be specific to an individual, not any group of people who may have used an exit.

Even if police check the boxes to make these drug traps technically legal, they still raise some practical questions, said John Mejia, legal director for the American Civil Liberties Union of Utah.

One is whether the operations are worth the manpower involved in order to scoop up what may be fairly insignificant offenses. But bigger than that, he said, is the issue of trust.

“It’s the sort of practice that, I think, makes people suspicious of what police are doing,” he said. “It’s important for the public to trust that the police aren’t constantly pulling these ruses that may hold up in court, but don’t feel like they’re keeping with the spirit of the Fourth Amendment.”

He’s got a point. The Bill of Rights isn’t a game designed to test how clever law enforcement can be in getting around the obstacles it sets up. Obviously they’ve demonstrated a lot of creativity.

When police get right up to the limits of the Fourth Amendment, it is important for law enforcement leaders, the courts and policymakers to make sure they are treading very, very carefully.

And the public — including stoners — should know how law enforcement is conducting its business.