“Legal Limit”

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  1. Introduction
  2. “Vehicle” and “Motor Vehicle”
  3. “Drive”
  4. “Drugs”
  5. “Legal Limit”
  6. Open Container
  7. Driving Under the Influence (DUI)
  8. Driving Under the Influence Per Se (“DUI Per Se”)
  9. Driving While Ability Impaired (DWAI)
  10. Second and Subsequent Offenses
  11. Underage Drinking and Driving (“UDD” or “Baby DUI”)
  12. Strict Liability
  13. Juveniles and Minors
  14. Evidence of Impairment
  15. Standardized Field Sobriety Tests (SFSTs)
  16. Drug Recognition Experts (DREs)
  17. Expressed Consent
  18. Breath Tests
  19. Blood Tests
  20. Prima Facie Case Requirement
  21. Preparing for Trial
  22. Voir Dire
  23. Expert Testimony
  24. Proving Chain of Custody
  25. Double-Refusals

There is no “legal limit” or “safe limit” for alcohol or marijuana in Colorado. Any amount of alcohol or drugs, in combination or alone, can be sufficient to constitute either DUI or DWAI if the drinking or drug use impairs that person’s ability to safety operate a motor vehicle.

“Presumed Safe” Limit of .05 BAC

There is, however, a “presumed safe” limit of .05 Breath Alcohol Content (“BAC”). If the defendant’s BAC was .05 BAC or less, the jury will likely be given a jury instruction stating that the jury may presume the defendant was not under the influence of alcohol and that the defendant’s ability to operate a motor vehicle was not impaired by the consumption of alcohol. § 42-4-1301(6)(a)(I).

Permissible Inferences of Under the Influence

There are recognized “illegal limits” that, if proven, allow a jury to make a “permissible inference” that the defendant was impaired at the time. If the defendant’s BAC was .08 or greater, the jury may infer the defendant was under the influence of alcohol. § 42-4-1301(6)(a)(III). If the defendant’s BAC was between .05 and .08, the jury may infer that the defendant’s ability to the defendant’s ability to operate a motor vehicle or vehicle was impaired by the consumption of alcohol. § 42-4-1301(6)(a)(II). In this scenario, the jury will also be instructed this inference may be considered with other competent evidence in determining whether or not the defendant was under the influence of alcohol. Id.

For marijuana cases, if the defendant’s blood contained 5 nanograms or more of delta 9-tetrahydrocannabinol per milliliter in whole blood, the jury may infer that the defendant was under the influence of one or more drugs. § 42-4-1301(6)(IV).

Beware of overreliance on these “limits,” especially in a marijuana impairment case. Not only do juries want to see other evidence of impairment, experts will tell you—and sometimes testify in favor of the defense—that the amount of delta 9 THC in the blood does not necessarily correlate to impairment in the brain. The science shows that the amount of delta 9 THC in the brain at the time of driving is what measures impairment, not the blood. Unfortunately, there are currently no field or laboratory tests that can reliably detect the amount of THC in the brain at the time of driving. Further, some studies suggest that frequent users of THC may have raised levels of THC in the blood even after a period of abstinence, which might make it difficult to know whether 5 ng THC in a blood test shows recent use. The amount of THC in the blood is therefore merely a crude proxy for how much THC may be in the brain, and the bulk of your evidence in a marijuana-impaired driving case should reflect that fact.

Resources

CDAC Videos

Marijuana Toxicology 101

Delta-8-THC

Using Research to Prove Your Case

Drugged Driving Series

The Seven Drug Categories Primer—Cannabis

National Resources

Investigation and Prosecution of Cannabis-Impaired Driving Cases