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Is CO’s 5-NG THC limit a reliable measure for impaired driving?

On Behalf of | Sep 8, 2017 | DUID |

The recreational use of marijuana may be legal under Colorado law, but that doesn’t mean you won’t be arrested for driving while under the influence of drugs (DUID) if you smoke pot before getting behind the wheel. In fact, Colorado law expressly states that there is a “permissible inference” that drivers are under the influence of drugs if their blood contains five nanograms or more of THC, which is the active ingredient in marijuana.

The problem with this five-nanogram limit, however, is that regular marijuana users — including medical marijuana patients — routinely have more than five nanograms of THC in their bloodstreams, even after the effects of the drug have long worn off.

This is because THC tends to stay in the body far longer than the effects last — meaning that frequent marijuana users may face possible DUID charges whenever they drive, regardless of whether they are actually impaired or not.

So why the 5-nanogram limit?

There is little scientific research available that actually sheds light on whether an individual with a THC level of five nanograms is impaired. This is why many people believe lawmakers simply took a shot in the dark when they created this limit.

In fact, at least one state, Nevada, set their THC driving limit at only two nanograms, which is incredibly low. Conversely, other states haven’t set a limit at all. Why the discrepancy? Could it be because there is no hard science when it comes to THC levels and driver impairment?

Sadly, we may never get a straight answer to these questions.