South Dakota Cannabis DUI — SDCL § 32-23-1 (5 ng/mL THC Per Se)

Last verified: May 2026

The DUI Penalty Schedule

The 5 ng/mL THC Per Se Threshold

South Dakota operates as a per se 5 ng/mL THC blood-concentration state for DUI purposes. According to the Marijuana Policy Project’s DUID policy page, only a small group of states have explicit per se numeric THC blood thresholds — Montana and Washington match South Dakota’s 5 ng/mL figure exactly, while Nevada, Ohio, Pennsylvania, and Illinois operate other per se thresholds.

A driver above 5 ng/mL is presumed impaired regardless of observable performance; the state need not prove impairment beyond the chemical test. This threshold is established through case law and DUI prosecution practice rather than as an explicit numeric statutory floor in § 32-23-1.

Under-21 Zero-Tolerance — SDCL § 32-23-21

SDCL § 32-23-21 makes it a Class 2 misdemeanor for any driver under 21 to drive "after having consumed marijuana or any controlled drug or substance for as long as physical evidence of the consumption remains present in the person’s body." Because cannabis metabolites can persist for weeks, a driver under 21 in South Dakota can be convicted of DUI based on a urinalysis taken long after any actual impairment has subsided.

Implied Consent & Refusal

Under SDCL § 32-23-10, any person operating a vehicle in South Dakota is deemed to have consented to chemical analysis of blood, breath, or other bodily substance. SD repealed its statutory right-to-refuse implied-consent in 2006; a refusal can be admitted into evidence at trial under SDCL § 19-19-513. After a DUI arrest, the arresting officer may require a blood draw.

DRE and Field Sobriety Programs

SD Highway Patrol, county sheriff’s offices, and major municipal departments run Drug Recognition Expert (DRE) programs trained to evaluate cannabis impairment through standardized field sobriety tests, divided-attention tasks, eye examinations, and chemical confirmation.

The Medical-Cardholder Carveout

SDCL § 34-20G-24 provides that a registered patient may not be deemed under the influence "simply due to the presence of cannabis metabolites or components in inadequate concentration to induce impairment." This is meaningful protection — but it does not displace the § 32-23-1 per se 5 ng/mL test. A cardholder above the 5 ng/mL threshold remains subject to DUI prosecution.

Aggravating Factors

• BAC 0.17% first-offense triggers mandatory chemical-dependency evaluation under SDCL § 32-23-2.1.
• Second-offense and above DUI convictions trigger participation in the 24/7 Sobriety Program (SDCL § 32-23-23).
• Death or serious injury — vehicular homicide / vehicular battery charges under SDCL Title 22 carry up to life imprisonment.
• 4th offense within 10 yr — Class 5 felony (up to 5 years, $10,000 fine).
• 5th+ offense within 10 yr — Class 4 felony (up to 10 years, $20,000 fine).

Practical Patient Notes

• Compassion-Act-equivalent registration is not a complete DUI defense. The 5 ng/mL threshold applies regardless of cardholder status.
• Patients on chronic dosing may exceed 5 ng/mL routinely. Plan dosing relative to driving exposure.
• Refusal triggers automatic suspension and is admissible at trial. The refusal calculus is more risk-laden in SD than in many states.
• Get DUI-experienced counsel. SD DUI defense is technical — the field-sobriety, chemical-test, and DRE-testimony issues require specialist defense.

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