Why Blood Tests Are Ineffective When Detecting Marijuana DUIs

Even in states where it is legal, it is typically illegal to drive under the influence of marijuana. Just like with alcohol, if you are pulled over and a law enforcement agent is able to prove that you are under the influence of marijuana, this can be used as an excuse to arrest and prosecute you. To determine if you are under the influence of marijuana, you might be given a marijuana breath test.

What "Under the Influence" Means

Being under the influence does not mean that you have simply ingested marijuana. It also requires that you have had your cognitive function impaired through the use of marijuana. You must be unable to drive your vehicle with the same skill and caution as someone who is not under the influence of marijuana. 

Detecting THC in the Body

One of the challenges of marijuana consumption is that unlike with alcohol, marijuana can remain in your system for a long time. You may even have THC in your system for weeks after you have used marijuana. Blood tests are able to determine how much THC is in someone's blood, but cannot determine how high that individual is and can't determine whether the marijuana would be enough to impair one's ability to operate a motor vehicle. For this reason, a breath test can actually be more effective at determining that someone has been driving under the influence of marijuana.

The Need for Marijuana Breathalyzer Tests

It requires very sensitive tools, but when THC can be detected in the breath of a motorist, this indicates that he or she has used marijuana very recently. Because the effects of marijuana can wear off quickly, law enforcement may need to use a breathalyzer test to prove that the motorist is under the influence.

Criminal Defense for a Marijuana DUI

When you have been arrested and charged with a marijuana DUI based on a blood test, you will want to bring this up with a DUI attorney at a local law firm. He or she will be able to use this to help you have your charges dismissed. While DUI breathalyzer test for marijuana has not yet been developed, it may eventually be available to police officers. But for now, there are methods you can use to cast doubt on the accusation that you were impaired as a result of marijuana consumption while operating a motor vehicle.