Riding a motorcycle demands alertness, coordination, and complete control. When cannabis enters the mix, law enforcement takes special measures to determine whether a rider is impaired. With evolving marijuana laws and inconsistent testing standards across states, understanding how police test for cannabis impairment can help motorcyclists make informed and lawful decisions on the road.
The Legal Groundwork
In most states, motorcyclists fall under the same impaired-driving laws that apply to any motor vehicle operator. The central rule is simple: riding under the influence of cannabis—or any substance that affects mental or physical faculties—is illegal. Some states have “per se” THC limits, setting thresholds (often 2 to 5 nanograms per milliliter of blood) beyond which a rider is automatically considered impaired. However, these limits are controversial, as THC affects individuals differently and can linger in the body long after intoxication fades.
Other states use “impairment-based” standards, meaning officers must observe behaviors or evidence that suggest a rider’s ability to operate safely is compromised. This approach can be subjective, relying heavily on officer interpretation and field tests.
Behavioral and Field Sobriety Testing
When a motorcyclist is stopped and suspected of cannabis use, the first line of assessment is behavioral observation. Police look for indicators such as:
- Erratic riding patterns or inconsistent speed
- Red or droopy eyes
- Slow reactions to questions
- The odor of marijuana
- Difficulty balancing when off the bike
If suspicion remains, officers often conduct Standardized Field Sobriety Tests (SFSTs)—the same tests used for alcohol impairment. These include:
- Walk-and-turn (divided attention)
- One-leg stand (balance and coordination)
- Horizontal gaze nystagmus (eye movement tracking)
While these tests can reveal impairment, cannabis affects the body differently from alcohol. THC-related impairment may not produce visible eye tremors, and factors like fatigue or tight motorcycle gear can also influence performance. As a result, SFSTs are not always conclusive for cannabis use.
Chemical and Laboratory Testing
If an arrest is made or further testing is warranted, riders may face chemical analysis:
- Blood Tests: Measure THC concentration but cannot determine the exact level of impairment.
- Saliva Tests: Detect recent cannabis use and are gaining popularity in roadside applications.
- Urine Tests: Identify THC metabolites but only confirm prior use, not real-time intoxication.
Despite growing technological interest, there’s no universal “cannabis breathalyzer” equivalent to alcohol testing. This lack of precision often complicates DUI cases involving marijuana.
Challenges for Riders
Motorcyclists face unique circumstances in impairment testing. Helmets, boots, and protective gear can affect field-test performance, while THC’s fat-soluble properties mean it remains in the body for days or even weeks. A rider who legally uses medical cannabis could test positive long after the psychoactive effects have dissipated.
Moreover, the margin for error is small. A slightly impaired motorist may correct course in a car—but a motorcyclist could easily lose balance or traction.
Riding Smart and Staying Legal
- Never ride if you’ve consumed cannabis recently.
- Know your state’s THC limits and implied consent laws.
- Understand that refusing a chemical test can lead to license suspension or additional penalties.
- Keep in mind that even legal or medical use can still result in a DUI arrest if impairment is suspected.
Riding Responsibly
For riders, cannabis laws can feel like a moving target. Law enforcement depends on a mix of visual cues, field tests, and lab results—none of which perfectly measure impairment. The safest approach is clear: wait until you are fully sober before getting back on your bike. Riding high not only risks your license—it risks your life.
Blog read: What to Do if You’re Pulled Over With Cannabis on a Ride