A 3-minute lesson from the Colorado course. Read the rules and examples, follow the handbook page references, and check your understanding before you move on.
Impairment isn't only about alcohol. Illegal drugs, marijuana, prescriptions and even cold medicine can impair you, and the law treats them the same way. Officers are trained to spot impairment whatever the cause.
Know the rule
Driving while impaired by drugs (illicit drugs, marijuana, prescription or over-the-counter medications) is illegal and carries the same penalties as alcohol impairment.
Tranquilizers, pain killers and over-the-counter allergy and cold medicines can impair driving. Check medication labels for warnings before you drive; if a label is missing or unclear, ask your doctor or pharmacist.
There is no THC permissible inference level for DWAI. Most marijuana-impaired drivers are convicted on behavioral symptoms as well as blood THC levels.
Impairment from using two or more drugs at the same time, in any combination, including alcohol, marijuana and medications. Mixing can increase the effects.
You took a prescribed painkiller whose label warns about drowsiness, then feel foggy behind the wheel. A valid prescription won't protect you: if you're impaired, you can be charged with DUI or DWAI just as with alcohol. Don't drive.
Check your understanding
Read the question, decide on an answer, then open it to check the explanation. These are Roadwise study questions based on the source handbook.
Under Colorado law, at what THC blood level is there a permissible inference that a driver was DUI?
2 nanograms per milliliter
8 nanograms per milliliter
10 nanograms per milliliter
5 nanograms per milliliter
Answer: 5 nanograms per milliliter
There is a permissible inference of DUI if a driver's blood contains 5 nanograms of THC per milliliter of blood.