Does Louisiana have a per-se THC limit for DUI?

No. Louisiana does not have a per-se THC blood-concentration threshold for DWI. Cannabis DWI cases are prosecuted on an impairment-based model under LRS §14:98 — the state must prove the driver was under the influence to a degree that rendered him incapable of safely operating a vehicle.

What happens if I refuse a chemical test in Louisiana?

Refusal triggers an automatic administrative license suspension under LRS §32:661 — minimum 180 days for a first refusal, escalating thereafter. The administrative suspension is independent of any criminal conviction or acquittal on the underlying DWI charge.

Louisiana DUI Cannabis & Cannabis Driving

Q: Is a Louisiana medical marijuana card a defense to DUI?

No. A medical-cannabis recommendation is not a defense to DWI in Louisiana. Patients face the same impairment standard as recreational users under LRS §14:98.

Legal Disclaimer: This information reflects Louisiana 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 Louisiana Board of Pharmacy or a qualified attorney. Cannabis remains illegal under federal law.

Last verified: April 2026

Louisiana Has No Per-Se THC Threshold

Driving under the influence in Louisiana is governed by LRS §14:98 — Operating a Vehicle While Intoxicated. Unlike states such as Washington (5 ng/mL active THC) or Nevada (2 ng/mL), Louisiana does not have a per-se THC blood-concentration threshold for DWI.

Cannabis DWI cases are prosecuted on an impairment-based model: the prosecution must prove that the driver was under the influence to a degree that rendered him incapable of safely operating a vehicle.

What Officers Look For

Louisiana State Police and most parish/municipal departments train officers in Standardized Field Sobriety Tests (SFSTs). A growing share are certified as Drug Recognition Experts (DREs) under the international DRE program. A DRE evaluation is a 12-step protocol involving:

Pulse and vital signs measurement.
Pupil examination under varying light conditions.
Divided-attention and balance tests.
Muscle-tone and reaction-time observation.
Vertical and horizontal gaze nystagmus tests.
A chemical screen (urine or blood) confirming substance class.

⚠️ The number of certified Louisiana DREs is in the low hundreds and concentrated in the New Orleans and Baton Rouge metros; rural arrests rely on SFST plus officer testimony.

Implied Consent — LRS §32:661

Under LRS §32:661, operating a motor vehicle on a Louisiana highway constitutes implied consent to a chemical test (breath, blood, or urine) when an officer has reasonable grounds to believe the driver is impaired. Refusal of the chemical test triggers an automatic administrative license suspension — minimum 180 days for a first refusal, escalating thereafter — independently of any criminal conviction.

DUI Penalty Schedule — LRS §14:98

LRS §14:98 imposes a graduated DWI scheme regardless of substance:

Offense	Jail	Fine	License
1st	10 days–6 months (most often suspended with probation)	$300–$1,000	Up to 1 year suspension; mandatory ignition interlock in some cases
2nd (within 10 years)	30 days–6 months	$750–$1,000	Longer suspension; mandatory community service
3rd	1–5 years (felony, at least 1 year hard labor)	$2,000	Multi-year suspension
4th	10–30 years (felony)	$5,000	Long-term revocation

A medical-cannabis recommendation is not a defense to DWI in Louisiana. Patients face the same impairment standard as recreational users.

Practical Defenses

Cannabis-DWI defense in Louisiana frequently turns on:

The absence of a per-se threshold, requiring the state to prove actual impairment beyond reasonable doubt.
The validity of SFST administration in field conditions (lighting, surface, weather).
The qualifications of the DRE performing the evaluation.
The reliability of urine or blood THC metabolite results, which can be positive for weeks after last use without reflecting active impairment.
The chain of custody for chemical samples.

Federal CDL Drivers

Commercial driver's license (CDL) holders in Louisiana are subject to federal DOT rules under 49 CFR Part 40. THC is a non-negotiable disqualifier regardless of state law or medical-card status. A positive cannabis test results in:

Immediate disqualification from operating a commercial vehicle.
Mandatory return-to-duty Substance Abuse Professional (SAP) evaluation.
Follow-up testing for at least 12 months after return.
Federal Drug and Alcohol Clearinghouse record visible to all CDL employers.

Boats, Aviation, and Federal Land

Boating — Louisiana DUI law applies on the water under §14:98.6; impairment standards similar.
Aviation — Federal jurisdiction under FAA; cannabis use is career-ending.
Federal land (national forests, military installations, NASA Michoud) — federal DUI statutes apply in addition to LRS §14:98.

If You Are Stopped

Be polite, comply with reasonable instructions. Louisiana enforcement around DWI stops can escalate quickly.
You can decline SFSTs in some cases — this is contested ground with no clean answer; consult a Louisiana criminal-defense attorney.
Refusing the chemical test triggers automatic license suspension regardless of criminal outcome (§32:661).
Request a Louisiana criminal-defense attorney immediately on detention.
Don't make admissions about consumption timing without counsel.

Cannabis DUI in Louisiana — LRS §14:98