Does Kentucky have a THC limit for driving?

No. Kentucky uses an impairment-based standard for cannabis DUI, not a per se THC nanogram limit. Marijuana is expressly excluded from the state's per se drug DUI list. Prosecution requires evidence of actual impairment.

Can medical cannabis patients get a DUI in Kentucky?

Yes. Having a medical cannabis card does not protect against DUI charges. However, SB 47 clarified that the mere presence of cannabis metabolites does not establish impairment. Officers must demonstrate actual impairment through field sobriety tests, DRE evaluation, or other evidence.

What are Kentucky DUI penalties?

First offense: 48 hours to 30 days jail, $200-$500 fine. Second: 7 days to 6 months, $350-$500. Third: 30 days to 12 months, $500-$1,000. Fourth or more within 10 years: Class D felony, 1-5 years prison, $1,000-$10,000 fine.

Can you refuse a drug test during a Kentucky DUI stop?

Under KRS 189A.103 (implied consent), driving on Kentucky roads constitutes consent to chemical testing when an officer has reasonable grounds to suspect impairment. Refusing a test triggers automatic license suspension and the refusal is admissible as evidence in court.

Kentucky Cannabis DUI — No THC Nanogram Limit

Legal Disclaimer: This information reflects Kentucky cannabis law as of April 2026 and is for educational purposes only. It is not legal advice. Laws and regulations change — always verify current rules with the Kentucky Office of Medical Cannabis or a qualified attorney. Cannabis remains illegal under federal law.

Last verified: April 2026

The Legal Standard: Impairment, Not Chemistry

Under KRS 189A.010, it is illegal to operate a motor vehicle while "under the influence" of any substance that impairs driving ability. Unlike alcohol (where 0.08 BAC creates a per se violation), cannabis DUI in Kentucky requires proof of actual impairment. There is no THC nanogram limit in Kentucky law.

This distinction matters enormously. Cannabis metabolites — particularly THC-COOH — can remain detectable in blood and urine for weeks after last use, long after any impairment has passed. A positive drug test alone does not prove a driver was impaired at the time of the traffic stop.

Marijuana is expressly excluded from Kentucky's per se drug DUI list. Prosecution requires evidence of actual impairment, not merely the presence of cannabinoids.
KRS 189A.010

SB 47's Metabolite Clarification

When Kentucky legalized medical cannabis through SB 47, legislators included an important protection: the presence of cannabis metabolites alone does not establish that a person was "under the influence." This provision was designed to protect medical patients who may test positive for THC metabolites during routine traffic stops even when they last used cannabis days earlier.

However, this does not give medical patients a free pass. If an officer observes signs of impairment — bloodshot eyes, slow reactions, erratic driving, the odor of freshly burned or vaporized cannabis — a DUI arrest remains entirely lawful even for cardholders.

How Cannabis DUI Is Investigated

Kentucky law enforcement uses a multi-step process to investigate suspected cannabis impairment:

Drug Recognition Expert (DRE) Program

Kentucky State Police and major departments employ certified Drug Recognition Experts who conduct a standardized 12-step evaluation protocol. The DRE assessment includes vital signs measurement, eye examinations (horizontal and vertical gaze nystagmus, lack of convergence), divided attention tests, and clinical indicators. DRE conclusions carry significant weight in court.

ARIDE Training Post-SB 47

Following the passage of SB 47, Kentucky expanded its Advanced Roadside Impaired Driving Enforcement (ARIDE) training program. ARIDE bridges the gap between basic field sobriety testing and the full DRE evaluation, training officers to recognize drug impairment indicators during routine traffic stops. Hundreds of Kentucky officers have completed ARIDE certification since 2023.

Law Enforcement Phlebotomists

Kentucky is among approximately 12 states that authorize law enforcement phlebotomists — officers trained and certified to draw blood samples during DUI investigations. This capability allows faster collection of blood evidence, which can be critical given how quickly THC levels decline in the bloodstream after consumption.

Implied Consent

Under KRS 189A.103, operating a motor vehicle on Kentucky roads constitutes implied consent to chemical testing (breath, blood, or urine) when an officer has reasonable grounds to believe the driver is impaired. Refusing a chemical test triggers automatic consequences:

First refusal: Mandatory license suspension and the refusal is admissible as evidence in court
Subsequent refusals: Enhanced penalties and extended suspension periods

DUI Penalties

Cannabis DUI carries the same penalties as alcohol DUI under KRS 189A. Kentucky uses a 10-year lookback period to determine whether a DUI is a first, second, third, or fourth offense:

Offense	Classification	Jail	Fine	License Suspension
1st (in 10 years)	Class B misdemeanor	48 hours – 30 days	$200–$500	30–120 days
2nd (in 10 years)	Class A misdemeanor	7 days – 6 months	$350–$500	12–18 months
3rd (in 10 years)	Class A misdemeanor	30 days – 12 months	$500–$1,000	24–36 months
4th+ (in 10 years)	Class D felony	1–5 years	$1,000–$10,000	60 months

Practical Guidance for Medical Patients

If you are a registered medical cannabis patient in Kentucky:

Never drive while impaired. A medical card is not a defense against DUI charges.
Keep your card accessible. Having your registry card can help clarify the situation during a traffic stop.
Understand the metabolite protection. A positive blood test alone should not sustain a conviction, but other evidence of impairment can.
Transport products properly. Cannabis must be in its original dispensary container and should be stored in a sealed, inaccessible area of the vehicle.

Kentucky Cannabis DUI & Driving Laws