Under Colorado law, you can be charged with Driving Under the Influence (DUI) even if the only substance in your system is a perfectly legal prescription medication. Many assume that a doctor’s prescription provides a blanket “safe” pass to drive. In reality, Colorado Revised Statutes § 42-4-1301 makes it unlawful to drive or operate a motor vehicle “while under the influence of … any drug to the extent that the person’s ability to operate a vehicle safely is impaired.” Here’s what you need to know if you take prescription meds and get pulled over in Greeley, Fort Morgan, or anywhere in Weld County.
Colorado’s “Drugged Driving” Standard
Colorado law treats impairment by drugs—prescription or otherwise—the same as impairment by alcohol. Under C.R.S. § 42-4-1301(1)(b), a driver is guilty of DUI if they operate a vehicle while “under the influence of … any drug” such that their “ability to operate the vehicle safely is impaired.” There is no distinction between illegal narcotics and legally prescribed medication. Even over-the-counter cough syrup can form the basis for a DUI if it renders you unsafe behind the wheel.
Express Consent and Chemical Testing
By driving on Colorado roads, you give “express consent” to submit to chemical testing—blood, breath, or urine—to determine your level of impairment (C.R.S. § 42-4-1301(3)(h)). Refusing a test can lead to an automatic license suspension, separate from any criminal charge. And while there is no per se “prescription-drug limit” like the .08% BAC threshold for alcohol, prosecutors can introduce toxicology reports showing detectable levels of impairing substances.
Common Prescription Medications That Can Trigger a DUI
- Opioid Pain Relievers (e.g., oxycodone, hydrocodone): These can cause drowsiness, slowed reaction time, and impaired judgment.
- Benzodiazepines (e.g., Xanax, Valium): Even small doses may produce significant sedation.
- Sleep Aids (e.g., Ambien, Lunesta): Residual “morning grogginess” can persist and interfere with safe driving.
- Muscle Relaxants (e.g., Flexeril): Can impair coordination and alertness.
- Over-the-Counter Medications (e.g., antihistamines, cold remedies): Ingredients like diphenhydramine can be highly impairing.
How Officers and Prosecutors Establish Impairment
- Field Sobriety Tests: Standardized tests (walk-and-turn, one-leg stand) can highlight balance and coordination issues.
- Officer Observations: Slurred speech, bloodshot eyes, slowed responses, or erratic driving may be documented in the arrest report.
- Toxicology Reports: Blood or urine tests showing any impairing drug, combined with expert testimony, can establish that your driving ability was compromised.
- Medical Records: Prosecutors may seek your prescription records to show you had a legitimate prescription, but also to argue you should have known about impairment warnings.
Defense Strategies When Prescription Pills Are the Only “Drink” in Your System
- Challenge the Traffic Stop or Arrest: If the stop lacked reasonable suspicion or the arrest lacked probable cause, evidence may be suppressed.
- Question Test Reliability: Field sobriety tests were developed for alcohol impairment. Their accuracy for prescription-drug impairment is debated.
- Medical Expert Testimony: A qualified toxicologist or physician can explain how your dosage, metabolism, and medical history affect impairment, and may demonstrate you were not actually impaired.
- Impeach Officer Observations: Video evidence (dash-cam or body-cam) can contradict an officer’s written report.
- Review Chain of Custody: Blood or urine samples must be handled properly; any break can render results inadmissible.
Why You Need an Experienced DUI Defense Team
At Bruno Lilly LeClere, PLLC, our attorneys have decades of combined experience defending DUI and DWAI charges—including those based solely on prescription medications. Founder Havilah Louise Bruno Lilly and Partner Andrew LeClere both served as prosecutors in the Weld County District Attorney’s Office. They know the state’s strategies and how to counter them.
- Learn more about our DUI/DWAI practice
- Meet Havilah Lilly on her bio page
- Meet Andrew LeClere on his bio page
If you’ve been charged with DUI after taking prescription medication—no matter how carefully you followed your doctor’s orders—call us right away. Early intervention can make the difference between a conviction and a complete defense.
Call Bruno Lilly LeClere, PLLC today at (720) 340-1373 or visit our contact page to schedule your confidential consultation. Your future is too important to leave to chance.