While the question is a common one, there is not an easy response. Too many factors involved for there to be a simple response. Among the factors are: how much marijuana did you smoke? How much tetrahydrocannabinol (THC) did the marijuana you have contain, and how much of it did your body absorb? Also, how long does it take your body to expel the THC it has absorbed so that it no longer has any effect on you? As you can see, the question is not easy to answer.
Colorado’s Legal Limit
You probably know that Colorado has legal limit for blood alcohol content, but there is also a legal limit for THC. Under the laws of Colorado, as a driver you are considered impaired if your blood contains 5 nanograms or more of THC. So an easy answer to the question of how long you should wait to drive after ingesting marijuana is until you have less than 5 nanograms of THC in your system. But even that answer is not as clear as you might like. In fact, Colorado’s legal limit law has come under a lot of scrutiny.
The scrutiny of the legal limit law came about soon after Colorado passed its legal limit law. Some of the complaints about the law were that the legal limit is too low, and that the test needed to detect the THC level is too intrusive. Regardless of the complaints, however, the legal limit is set at 5 nanograms. So even if you can operate fine with 5 nanograms of THC in your blood, the law will hold that against you. On the other hand, if your physical makeup is such that less than 5 nanograms of THC does impair your driving, than that is a problem as well.
Proving You Were Not Impaired
One positive aspect of the legal limit law may surprise. If you were to be pulled over, tested, and found in violation of the 5 nanogram law, you have a chance to prove that the levels of THC in your blood did not impair your driving. To prove it, you would have to put on evidence showing that you were not impaired. However this is difficult to do. It is best used as a last resort, and better to avoid altogether.
Implied Consent Rule
You may wonder how the police are allowed to test drivers’ blood at all. In addition to passing recreational marijuana laws, legal limit laws, and others, Colorado has an implied consent law too. That means that every driver in Colorado has consented to be tested for blood or other drugs if a police officer has reasonable grounds to believe a driver is under the influence of drugs or alcohol. And the officer can test blood, saliva, urine, or breath under the law.
So How Long Should You Wait?
The immediate answer is that you should wait until the THC levels in your blood are below 5 nanograms. Being certain you are not under the influence is important because getting caught carries multiple, severe penalties. You could lose your license, go to jail, have a conviction on your record, or more.