Wyoming Cannabis DUI — Impairment-Based, NO Per Se THC Limit

Legal Disclaimer: This information reflects Wyoming cannabis law as of June 2026 and is for educational purposes only. It is not legal advice. Laws and regulations change — always verify current rules with the Wyoming Department of Health (Hemp Extract Registration); Wyoming Department of Agriculture (Industrial Hemp Program) or a qualified attorney. Cannabis remains illegal under federal law.

Last verified: May 2026

The DUI Schedule

Offense	Class	Penalty
1st DUI (within 10 years)	Misdemeanor	6 months / $750
2nd DUI (within 10 years)	Misdemeanor	7 days–6 months / $200–$750; 1-year IID
3rd DUI (within 10 years)	Misdemeanor	Up to 6 months; 24/7 sobriety eligible
4th+ DUI (within 10 years)	Felony	7 years / $10,000; 5-year-to-life IID
DUI with serious bodily injury	Felony	10 years / $2,000–$5,000
Aggravated homicide-by-vehicle	Felony	20 years
Passenger under 16	Enhanced	First: 1 year; subsequent: 5 years

Source: Wyo. Stat. Ann. § 31-5-233 + § 31-6-102 (implied consent). Wyoming has NO per se THC limit — cannabis DUI is impairment-based under § 31-5-233(b)(iii)(B). A medical recommendation in another state is NOT a defense (§ 31-5-233(d)). THC metabolite detection windows (1–7 days for occasional users; weeks for heavy users) interact with the "internal possession" doctrine to create unusual exposure for cross-border returning Wyoming residents.

The Two Theories — Wyo. Stat. § 31-5-233

Per se alcohol — BAC ≥ 0.08% (§ 31-5-233(b)(i)–(ii)). Does NOT apply to cannabis. Wyoming has NO per se THC limit.
Under the influence to a degree which renders the person incapable of safely driving (§ 31-5-233(b)(iii)) — the operative theory for marijuana DUI. Subsection (b)(iii)(B) covers controlled substances; (b)(iii)(C) covers combinations.

The impairment-only framework places substantial weight on field sobriety tests, drug recognition expert (DRE) testimony, and circumstantial evidence of impairment. The framework is more defendant-friendly than per se threshold states (CO/MT/SD 5 ng/mL; WI any detectable) but still produces conviction-level exposure.

The Out-of-State Medical Card Bar

Wyo. Stat. Ann. § 31-5-233(d) provides that a valid medical recommendation in another state is not a defense. A Wyoming driver lawfully using medical cannabis under a Colorado / Montana / California / Florida / etc. medical card cannot use that authorization as a DUI defense. The framework parallels Alabama’s § 32-5A-191(d) and similar state statutes.

Field Sobriety Tests

HGN (Horizontal Gaze Nystagmus) — designed for alcohol; defense attorneys note poor calibration to cannabis impairment. HGN is generally not reliable for cannabis.
Walk-and-turn — tests divided attention.
One-leg stand — tests balance and divided attention.

FSTs are not legally compelled in Wyoming. A driver may decline politely. However, declination may produce additional officer suspicion and lead to chemical-test request under implied consent.

Drug Recognition Expert (DRE) Protocol

Wyoming Highway Patrol maintains DRE-certified troopers. The 12-step DRE protocol covers vital signs, eye examinations, divided-attention tasks, and chemical confirmation. DRE testimony is admissible in WY courts.

Implied Consent — Wyo. Stat. § 31-6-102

Wyoming has implied consent: any person operating a vehicle in the state has consented to chemical analysis of blood, breath, or urine. Refusal triggers:

6-month administrative license suspension (1st refusal).
Up to 18 months for habitual offenders.
Officers can also obtain a search warrant for blood draw if implied-consent refused.

Combined "Internal Possession" + DUI Risk

The single most underestimated risk for cross-border returning Wyoming residents: a Wyoming resident lawfully consuming cannabis in Colorado on Saturday and driving home Sunday faces both a potential DUI under § 31-5-233(b)(iii)(B) and a potential independent possession charge under § 35-7-1031(c) based on metabolites alone. See internal possession page.

Detection Windows

THC metabolites detectable in blood for 1-7 days for occasional users.
Weeks of detection for heavy users.
THC-COOH (the principal metabolite tested) does not correlate well with present impairment.

4th-and-Above DUI Felony Exposure

Wyoming’s 4th DUI within 10 years is a Class H felony with 7 years prison and $10,000 fine plus 5-year-to-life ignition interlock. The penalty progression is severe; defense counsel is essential.

Aggravating Factors

DUI with serious bodily injury: Felony 10 years / $2,000-$5,000.
Aggravated homicide-by-vehicle: Felony 20 years.
Passenger under 16: Enhanced penalty — first offense 1 year; subsequent 5 years.