New Devices Test Drivers for THC and Marijuana Impairment

You’ve been hearing about drunk driving for decades. You know it’s wrong, illegal, and dangerous.

Even someone who chooses to drive while drinking is aware of these undisputable facts; they just decide to do it anyway. Whether that results in their own death or injury, death or injury to another person (or multiple people), or criminal charges… these are the risks you take when you drive while impaired by alcohol.

Most states’ laws specify that drivers must not be under the influence of alcohol or other substances—“Driving While Ability Impaired” (DWAI) or “Driving Under the Influence” (DUI), which can include anything that affects your ability to drive. 

But what about marijuana?

Where is marijuana legal?

While some states have made marijuana legal, it’s still illegal in ALL STATES to drive while impaired by the substance.

How does marijuana affect driving?

Studies show that marijuana (or driving “high”) can slow your reaction time, impair judgment of distance, and decrease coordination.

Therefore, drivers should treat marijuana the same as alcohol or any other drug—if you’re using the substance, don’t drive.

How is driving while high on marijuana regulated?

This is a tricky question; a police officer can determine whether a person is drunk by performing a Breathalyzer test. A Breathalyzer measures blood alcohol content to determine if the driver is above the legal limit, just by breathing into a small device. 

But if an officer observes an erratic driver, if there’s a crash, or there is some other infraction, how do they know if they’re high?

That’s what the Minnesota State Patrol sought to figure out.

Beginning in 2024, MSP officers were equipped with a device that analyzes saliva for THC (that’s Tetrahydrocannabinol, or the compound in marijuana that makes people high). 

The device isn’t pocket-sized like a Breathalyzer; it’s about the size of a coffee maker or an old-school computer tower. Minnesota, Alabama, Michigan, Indiana, Colorado and Wisconsin have piloted these devices in recent years. 

It’s important to detect when someone is driving while impaired by THC, but the device has limitations. One is that THC can stay in a person’s system for days, even though they are no longer high or impaired. So, there’s a risk that people could be arrested for driving under the influence even if they were actually safe to drive at that time. 

The question facing officials and legislators is this: Is it worth it? Is this device, which can detect THC in saliva, the best way to determine if someone is impaired and hazardous on the road? 

One Colorado police chief says it’s one tool in the officers’ toolbox that can help detect a hazardous driver. It can be combined with other apps and observations that would test a person’s cognitive ability if they cause a crash or are suspected of being impaired.

Awareness.

An expert on cannabis policy says that while a tool or device that can measure impairment is a step in the right direction, the better and more important way to combat driving while impaired by marijuana or THC is to continue to educate the public about how dangerous it is.

Just like public safety campaigns over the years since the 1970s have made it well-known that drunk driving is dangerous, it needs to be the same for marijuana. Now that the drug is widely available and legal in multiple states, the onus is on legislators and other officials to make sure people understand that driving high is just as dangerous as driving drunk… maybe worse.