Clear Rule

The rules around marijuana use can be confusing. But when it comes to marijuana use and driving, all you need to remember is one clear rule:

Driving impaired is illegal everywhere.

Driving impaired is illegal everywhere.

Everything else can get kind of hazy.

When you feel different, you drive different. Everything else can get kind of hazy. So, if you want to think through some of the things experts and leading researchers are learning about marijuana’s effect on your driving, you can do that here.
Index
Issue
4
Mixing Substances
Subject

Combining marijuana with alcohol results in impairment even at doses that would be insignificant were they of either drug alone.

Why it matters?

Worse still, marijuana and alcohol, when used together, have additive or even multiplicative effects on impairment.

Consequently, on the basis of cognitive studies, it seems reasonable to propose that using marijuana along with other substances may increase the risk of being involved in a major, and even fatal, traffic crash.

Related Issues: Increased Crash Risk2

Clarity Level
Low
Abstract
This study reviews the scientific evidence on the effects on driving while intoxicated with marijuana and contrast this with the effects of alcohol intoxication.
Abstract
This study reviews the scientific evidence on the effects on driving while intoxicated with marijuana and contrast this with the effects of alcohol intoxication.
This ranking indicates how “settled” we feel an issue is. Issues that are clear-cut, fully-researched, and conclusive have a “High” clarity level. Issues that are involved in ongoing research, or focus on matters that require additional study, have “Medium” or “Low” clarity levels — depending on the amount and strength of supporting research.