Alabama Cannabis DUI — § 32-5A-191 (Impairment-Based, No Per Se THC Limit)

Last verified: May 2026

The DUI Penalty Schedule

Why "Impairment" Is the Standard

Alabama’s cannabis DUI statute does not specify a numerical THC threshold like Colorado’s 5 ng/mL or Ohio’s 2 ng/mL. Instead, § 32-5A-191(a)(3) makes it unlawful to drive "under the influence of a controlled substance to a degree which renders him or her incapable of safely driving." The prosecutor must prove actual impairment — through driving observations, field sobriety tests, the officer’s training and experience, and (often) drug-recognition-expert (DRE) testimony.

A blood or urine test showing THC or THC metabolites is not alone sufficient for conviction; the test result is one piece of evidence the prosecutor uses to corroborate the impairment finding. THC’s long detection window — up to 30+ days for chronic users — means a positive test does not establish recent use or current impairment.

The Compassion Act Carveout (And Its Limits)

Section § 32-5A-191(d) expressly states that "the fact that any person charged with violating this section is or has been entitled to use such drug under the laws of this state shall not constitute a defense." A registered medical-cannabis patient driving with detectable THC and showing any sign of impairment can be charged and convicted under the same statute as a recreational user.

What the medical card does provide is the underlying authority to possess the cannabis lawfully under § 20-2A-1 et seq. The DUI charge under § 32-5A-191 is independent of the possession question.

Implied Consent — § 32-5A-194

Alabama’s implied-consent statute provides that any person who operates a motor vehicle on a public road has consented to chemical testing of breath, blood, or urine. Refusal of a chemical test triggers an automatic 90-day driver’s license suspension on first offense, regardless of whether the underlying DUI charge results in conviction. Refusal-suspension proceedings are administrative; they run separately from the criminal case.

Refusal can also be used as evidence in the criminal trial — the prosecutor may argue the refusal demonstrates consciousness of guilt.

Field Sobriety Tests & Drug Recognition Experts

Alabama law-enforcement officers conduct standardized field sobriety tests (SFSTs) when cannabis impairment is suspected: horizontal gaze nystagmus (HGN), walk-and-turn, one-leg stand. HGN is generally considered unreliable for cannabis impairment (cannabis does not produce horizontal gaze nystagmus the way alcohol does), but the test continues to be used. Some defendants have successfully challenged HGN-based cannabis DUI prosecutions on Daubert grounds.

Drug Recognition Experts (DREs) are officers who have completed an additional 12-step protocol training (vital signs, eye examinations, divided-attention tests, etc.) and are credentialed to testify about drug-class impairment. ALEA, Birmingham PD, Montgomery PD, and most major Alabama agencies maintain DRE-trained officers.

Aggravating Factors

• Child under 14 in vehicle — doubles all minimum punishments under § 32-5A-191(j).
• BAC 0.15+ — ignition interlock requirement on first offense.
• Prior convictions within 5 years — second offense escalates to mandatory 5 days incarceration; third offense escalates to mandatory 60 days.
• 4th offense — Class C felony: 1 year 1 day to 10 years state prison.
• Death or serious injury — vehicular homicide / assault charges under § 13A-6-2 / 13A-6-21 carry up to life imprisonment.

Implied Consent + Compassion Act Patients

For Compassion Act registered patients, the implied-consent calculus is unusually fraught. Patients have detectable THC in their blood or urine continuously, even days after their last dose. A traffic stop — even a routine speeding stop — can escalate to DUI investigation if the officer suspects impairment based on demeanor, vehicle condition, or prior knowledge. Refusing the chemical test triggers automatic 90-day suspension. Submitting to the test produces a positive result, which the prosecutor will use as evidence even though it does not prove impairment.

Compassion Act patients should consider: (1) consulting with their certifying physician about safe-driving timing relative to dosing; (2) keeping documentation of the medical card and current dispensing receipts in the vehicle; (3) declining to make incriminating statements at traffic stops (right to remain silent under U.S. Const. amendment 5).

Practical Notes

• Get DUI-experienced counsel. Alabama DUI defense is technical — the field-sobriety, breath-test, blood-test, and DRE-testimony issues require specialist defense.
• Refusal triggers automatic suspension. The administrative-suspension proceeding has its own timeline (typically 10 days to request a hearing); miss the deadline and the suspension takes effect by default.
• Compassion Act cards do not protect against DUI. Patients face the same charge as recreational users.
• Vehicular homicide is a Class A felony. If a DUI causes a fatality, the defendant faces 10 years to life.