blog home Drug Crimes Roadside Testing for Marijuana: Knowing Your Rights and the Process

Roadside Testing for Marijuana: Knowing Your Rights and the Process

By Peters & Nolan, LLC on June 18, 2020

As cannabis use has been legal in Colorado since 2012, many rules and regulations have had to be drawn up in regard to people driving while high. Marijuana, like alcohol, can impair your reaction time, making it dangerous to drive after smoking or consuming the drug. However, testing for recent marijuana use is difficult at best and almost impossible at worst. That is why, in a new age with legal recreation marijuana use, you should know your rights when it comes to roadside testing.

How You May Be Tested

There are many different tests used to determine if someone has been driving while high. The reliability of these tests, however, has been called into question many times since marijuana first become legal in Colorado.


Saliva can be used to test for marijuana consumption. Unlike many of the other tests on this list, the saliva test can be done roadside, though it may take up to ten minutes to complete. The officer will take a swab sample of your mouth and then run it through several tests, as this swab test is also used for other drugs such as cocaine, methadone, and crystal meth, in order to determine your blood THC levels. However, there is some controversy as to whether or not this method of testing is actually accurate.


Hair can, surprisingly, be used to determine THC blood levels. Although, unlike with the swab tests, this must be done in a lab. This means that if the officer suspects that you are driving high, they may choose to take you to the police station for further testing. There a small amount of your hair will be removed using scissors. However, hair tests are also unreliable as it detects drug usage over a long period of time, usually around 90 days, rather than immediate use.


Blood tests are the most accurate tests that are currently available for cannabis use. They also cannot be given roadside, so you will be asked to go to the police station where the officers there can take a blood sample. While a blood test may give a more accurate timeline of consumption than hair tests, it still cannot tell officers if you used cannabis recently enough to be considered high. Meaning, these tests may also not prove that you have broken the law.


Urine tests were once the standard when it came to drug tests, but these days they are not used as regularly. An officer may administer a urine test at the police station if they, for whatever reason, cannot get a saliva or blood test. Like a blood test, urine will not be able to give an accurate measure of how recently you used cannabis.


Because the tests for marijuana consumption are so inaccurate, most officers will choose to administer roadside tests, rather than bother with lab results. These tests can include things like shining a small light in your eyes to check for proper pupil dilation, asking you to walk a straight line and then turn around, or to stand on one leg for an extended period of time. While these tests can help an officer determine if you are impaired, you should remember that they are also based off of the officer’s observations and opinions, which means assumptions and biases can play a heavy role in whether you are arrested or not.

Legal Limits of Marijuana

Tetrahydrocannabinol, usually known as THC, is the main indicator on whether an individual as smoked or otherwise consumed marijuana. During blood tests, police officers will look for your THC levels, which will then help them determine if you were driving over the legal limit. Or will it?

THC can stay in the bloodstream for weeks after cannabis consumption, long after the initial effects of the drug have worn off. In Colorado, the legal driving limit of marijuana is only 5 nanograms per milliliter of blood. If that sounds like a miniscule amount of cannabis to you, you would be right. It is incredibly easy to end up with 5 nanograms of THC in your system. It is possible to go over that amount just from being in the same room of someone smoking marijuana, without actually partaking of it yourself.

This, in an addition to the fact that THC can stay in your bloodstream for such an extended amount of time, means that anyone who consumes cannabis regularly, whether it be for recreational or medicinal use, is essentially barred from driving legally in Colorado.

Your Rights

If you drive using a license in Colorado, then you are assumed to have provided “express consent” to any chemical tests the officer believes are necessary following a lawful DUI or DWAI arrest. You are not legally allowed to refuse a chemical test. Refusing these tests can carry some serious consequences, such as having your license suspended for a year, having restricted driving rights after your suspension ends, and having to take classes on driving while high or intoxicated.

However, roadside tests, such as standing on one leg or walking and turning, are not required. You may legally refuse them without facing any consequences for doing so. That being said, the officer questioning you may then decide to issue an arrest and make you take a chemical test. Given how inaccurate those tests are, they are not impossible to fight, even if you test over the legal limit.

If you have been arrested for driving while high, you may be facing harsh punishments that could turn your life upside down. Your best chance of walking away from the arrest with a clean record is to contact an experienced criminal defense attorney. We at Peters & Nolan, LLC have years of drug crime defense under our belts. Call us today at (970) 243-4357 and learn how we can defend you.

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