Wyoming "Internal Possession" Doctrine — Wyo. Stat. § 35-7-1031(c)

Last verified: May 2026

The Statutory Foundation

Wyo. Stat. Ann. § 35-7-1031(c) provides: "It is unlawful for any person knowingly or intentionally to possess a controlled substance." The statute does not specify whether "possession" requires physical possession of the drug or extends to metabolites in the body. Wyoming caselaw — similar to South Dakota’s Schroeder/Whistler line of cases — has historically allowed prosecutions on metabolite evidence alone.

The Cross-Border Travel Trap

The most consequential implication for Wyoming residents and visitors:

1. Resident travels to Colorado (or Montana) over a weekend.
2. Lawfully consumes cannabis in the legal-cannabis state.
3. Returns home to Wyoming with no physical cannabis in the vehicle.
4. Stopped (for any reason) by Wyoming Highway Patrol or local law enforcement.
5. Tested via blood draw under implied consent (§ 31-6-102).
6. Tests positive for THC metabolites.
7. Faces:
   • DUI charge under § 31-5-233(b)(iii)(B) (impairment-based, no per se threshold).
   • Independent possession charge under § 35-7-1031(c) based on metabolite presence alone.

Detection Window Reality

THC metabolite detection windows compound the exposure:

• Occasional users: 1–7 days detection in blood; longer in urine.
• Heavy users: 30+ days detection.
• THC-COOH (the principal metabolite tested) does not correlate well with present impairment but is detectable for extended periods.

For chronic legal-hemp consumers (delta-8, hemp-derived delta-9, THCA flower) prior to SF 32 (2024), THC-COOH presence has been measurable for weeks. The "internal possession" doctrine creates ongoing legal exposure regardless of consumption legality at the source.

Comparison with South Dakota

South Dakota has the most-cited "internal possession" doctrine: State v. Schroeder (2004 S.D. 21) and State v. Whistler (2014). South Dakota Senate Bill 83 (2025) reduced first/second-offense ingestion under SDCL § 22-42-5.1 from a Class 5 felony to a Class 1 misdemeanor effective July 1, 2025. The doctrine itself survives. Wyoming’s framework is similar but has not been the subject of comparably high-profile case law.

Hemp Extract Act 2015 Carveout

Wyoming Hemp Extract Act 2015 (HB 32, codified Wyo. Stat. §§ 35-7-1901–1904) provides a narrow affirmative defense for cardholders with intractable epilepsy possessing hemp extract (≤0.3% THC, ≥5% CBD). The carveout does not extend to metabolite-only "internal possession" exposure for products with any THC content.

Practical Implications

• Cross-border travel + drug test = real exposure. Even with no product in the vehicle, metabolite testing produces possession-charge risk.
• Plan ≥24–48 hours of separation between consumption and a Wyoming border crossing for occasional users.
• Heavy users: THC-COOH detectability extends for weeks; cross-border travel is high-risk indefinitely.
• Out-of-state medical recommendation is NOT a defense under § 31-5-233(d).
• Hemp Extract Act cards do NOT extend to internal-possession exposure for non-CBD-only products.
• Refuse field sobriety tests politely. Implied consent under § 31-6-102 covers chemical tests; FSTs are not legally compelled.

The Combined DUI + Possession Risk

The combination of:

• Impairment-only DUI (no per se threshold favors prosecutors who can present any impairment evidence).
• "Internal possession" doctrine (metabolites support possession charge).
• 0.3-gram concentrate felony cliff (any concentrate post-cross-border = felony).
• Out-of-state medical recommendation not a defense.

...makes Wyoming one of the most legally-exposed states for cross-border returning Wyoming residents.

Related on this site: The Wyoming 0.3-Gram Concentrate Felo..., Wyoming Cultivation & Distribution, Wyoming Cannabis DUI.