Yes, it is possible to know if someone is driving high. Police use specialized investigative techniques for suspected marijuana DUIs in Colorado, including standardized field sobriety tests (SFSTs), drug recognition experts (DREs), and blood tests. However, these techniques are inherently flawed, which means that you should defend your charges in the event of an arrest.

Although Colorado legalized marijuana in 2012, it is still illegal to drive impaired within the state. In this post, a defense attorney helps you understand marijuana DUI testing methods, their flaws, and how to fight charges in the event of an arrest.

How Can Police When You Are Driving High?

The initial stages of a marijuana DUI investigation are similar to a drunk driving case. Police will stop the driver for a traffic violation, such as driving too slowly, failing to obey traffic signals, or swerving. Upon stopping your vehicle, they are already looking for signs of impairment and marijuana-related items in plain sight.

Field Sobriety Testing

If the responding officer suspects that you are under the influence of drugs or alcohol, they will initiate a field sobriety testing sequence. They perform these tests to determine whether or not the individual is impaired and rule out the possibility that alcohol may be responsible for the impairment.

Drug Recognition Experts

Once you pass the field sobriety test, the officer is not out of legal options to determine if you are driving high. Police must decide whether to call a drug recognition expert (DRE). Depending on the facts, they may arrest the driver, or a DRE may need to continue the investigation.

Blood Tests

A blood test could confirm the presence of marijuana in your body. You can face a marijuana DUI if your blood contains more than five (5) active THC nanograms per milliliter. Police can use this evidence as probable cause to arrest you, and prosecutors will undoubtedly raise your blood test results in court.

What Is a Drug Recognition Expert?

Drug recognition experts, or DREs, are police officers with specialized training to detect if someone is driving high or drunk. They utilize a 12-step evaluation process to make a determination for DUIs related to cannabis, depressants, hallucinogens, inhalants, narcotics, stimulants, and more. Colorado has used a DRE program since 1987.

The 12 components of a DRE evaluation include the following:

  1. Arresting officer interview
  2. Breath alcohol test
  3. Darkroom examinations
  4. Divided attention tests
  5. Evaluator’s opinion
  6. Eye examinations
  7. Injection site inspections
  8. Muscle tone check
  9. Preliminary examination
  10. Toxicological examinations
  11. Vital signs examinations
  12. Your statements to the police

As you can see, numerous testing methods can tell police more information about whether you are driving high. However, these testing procedures do not always consider the full scope of facts and circumstances. For example, some health conditions and medications can produce false positives, which means that you should seek legal help if arrested for driving high in Colorado.

Are Marijuana DUI Tests Accurate?

Marijuana DUI tests are not always accurate. Even when detected, tetrahydrocannabinol (THC) levels are not indicative of a driver’s impairment. Given Colorado’s legal limit for driving under the limit of drugs, drivers can face a wrongful arrest.


Current research indicates that measuring impairment by blood THC concentration is unreliable, and drivers may be subject to unjustified charges. Therefore, it is critical that you fight them in court if you do not think you should accept responsibility for the alleged crime.


Blood THC concentrations are not an effective indicator of impairment in the context of drugged driving. Further, some people exceeding the legal blood THC concentration limit in Colorado may not truly be impaired. The officer must also prove they observed physical signs of impairment.

People without signs of impairment should never be arrested or charged. Even still, some typical symptoms of marijuana use, such as bloodshot eyes, are caused by other conditions. Therefore, it is possible for sober drivers to show apparent signs of marijuana use.

These tests are highly subjective for determining whether a person is impaired by marijuana use. Any Colorado criminal defense lawyer will advise that you fight your DUI charges in court.

How to Fight Marijuana DUI Charges in Colorado

People charged with driving high may have grounds to challenge their charges, given the difficulty of identifying drivers under marijuana impairment. In this position, people may find it beneficial to consult with a DUI attorney as a vital first step. You have the right to argue your case at trial to challenge the prosecutor’s theory against you and uncover evidence that exonerates you.

Call for a Free Consultation

At Chaput Law, our legal team is ready to help you defend against criminal charges and other legal issues. Reach out today for a Free Consultation about your legal options in Colorado.

Categories: DUI