SC Cannabis DUI — No Per Se THC Limit (§ 56-5-2930)

Last verified: May 2026

Statutory Framework

S.C. Code § 56-5-2930 makes it unlawful for a person to drive a motor vehicle in South Carolina "while under the influence of alcohol to the extent that the person’s faculties to drive a motor vehicle are materially and appreciably impaired, under the influence of any other drug or a combination of other drugs or substances which cause impairment to the extent that the person’s faculties to drive a motor vehicle are materially and appreciably impaired, or under the combined influence of alcohol and any other drug or drugs or substances which cause impairment…." Cannabis falls squarely within "any other drug." There is no separate marijuana-DUI statute and no separate set of penalties for cannabis-impaired driving; the same graduated penalty schedule that applies to alcohol DUI applies to cannabis DUI.

The "Materially and Appreciably Impaired" Standard

South Carolina’s impairment standard requires the state to prove, beyond a reasonable doubt, that the driver’s ability to operate the vehicle was "materially and appreciably impaired" by cannabis. This is a fact-intensive jury question rather than a mechanical concentration test. The state typically presents:

• Officer observations. The arresting officer’s testimony as to driving behavior (lane drift, slow reaction, poor decision-making at intersections), demeanor at the stop (red eyes, glassy-eyed appearance, slurred speech, slow speech, slow movement), the smell of marijuana, the presence of paraphernalia or product in the vehicle, and the driver’s admissions.
• Standardized Field Sobriety Tests (SFSTs). The three-test NHTSA battery: Horizontal Gaze Nystagmus (HGN, principally an alcohol indicator and of disputed utility for cannabis), Walk-and-Turn, and One-Leg Stand. SFSTs were developed and validated for alcohol; their utility for cannabis impairment is contested by the defense bar.
• Drug Recognition Expert (DRE) evaluation. A specially trained officer’s 12-step evaluation, ordinarily conducted at the booking facility, includes vital signs, eye examinations (HGN, vertical gaze nystagmus, lack of convergence), divided-attention tests, a dark-room examination of pupil size, muscle-tone assessment, an interview and opinion. DRE conclusions are admissible but vigorously challenged by defense counsel as to scientific validity. See implied-consent + DRE page.
• Toxicology. Blood (more probative) or urine (less probative) testing for THC and metabolites. Toxicology results in South Carolina are corroborative evidence rather than dispositive; without a per se threshold, even a high THC concentration is only one piece of the impairment puzzle.

Why "No Per Se Limit" Is Not Pro-Defendant

It would be a mistake to read the absence of a per se threshold as an advantage to the cannabis-using driver. In jurisdictions with per se thresholds, a driver below the threshold may rebut impairment with the toxicology result. In South Carolina, the absence of a threshold cuts both ways: the state cannot prosecute purely on a number, but the defense cannot rely on a number to defeat prosecution either. With sufficient officer-observation, SFST, and DRE evidence, the state can secure a conviction on a driver with a relatively modest THC concentration if the totality of impairment evidence is persuasive to a jury. Conversely, in close cases, a defense focused on the unreliability of SFSTs and DRE protocol for cannabis can succeed where it would fail under a per se rule.

Penalty Schedule

DUI in South Carolina is a graduated misdemeanor that becomes a felony on a fourth or subsequent offense. With no per se THC threshold, marijuana DUI is generally charged at the "no-BAC-inference" level (the higher penalty range of two tracks for alcohol DUI) and proven through impairment evidence:

• 1st DUI (drug-only, no BAC inference): 48 hours to 30 days (or 48 hours of community service); $400 fine.
• 2nd DUI: 5 days to 1 year; $2,100–$5,100 fine.
• 3rd DUI: 60 days to 3 years; $3,800–$6,300 fine.
• 4th or subsequent DUI: 1 to 5 years felony; discretionary fine.

All convictions require completion of an Alcohol and Drug Safety Action Program (ADSAP) before reinstatement of driving privileges. ADSAP completion includes assessment, education, treatment when indicated, and an aftercare component.

The § 56-1-286 Six-Month Suspension

Independent of any DUI conviction, conviction for any controlled-substance offense involving marijuana or hashish — including a simple-possession misdemeanor — triggers a mandatory six-month driver’s license suspension under S.C. Code § 56-1-286, even if the offense itself was unrelated to driving. The provision predates modern DUI enforcement and reflects a broader 1980s-era federal incentive structure linking state license-suspension regimes to federal highway funds. In practice, § 56-1-286 means a defendant convicted of simple possession on a passenger-side stop — with no claim of impairment — nonetheless loses driving privileges for six months. See tax-stamp + license suspension page.

Out-of-State Medical or Recreational Status Is Not a Defense

South Carolina does not honor any out-of-state medical-cannabis card, and the absence of a per se threshold does not provide a back-door safe harbor for out-of-state medical patients driving in SC. A Florida medical-cannabis cardholder driving on I-95 from Daytona to Charleston with cannabis purchased lawfully in Florida is exposed to (a) state-law possession charges under § 44-53-370 if the cannabis is in the vehicle, (b) DUI under § 56-5-2930 if the state can prove material and appreciable impairment, and (c) the § 56-1-286 collateral six-month license suspension on conviction. A Maryland adult-use buyer driving I-95 south is in equivalent exposure. See Virginia I-95 page.

Prevalence of Cannabis DUI in South Carolina

Statewide DUI arrests, including drug-only DUIs, are reported in SLED’s annual Crime in South Carolina publication. SLED’s 2024 report showed a 12.5% decrease in drug-law violations from 2023 to 2024; marijuana was the single most common drug type at 49.7% of drug offenses in 2023, with stimulants second at 19.8%. South Carolina recorded 10,325 marijuana possession arrests and 1,185 marijuana sales arrests in 2023 per FBI National Incident-Based Reporting System (NIBRS) data — among the highest absolute totals in the country. The cannabis-DUI subset of these totals is not separately broken out, but defense counsel report cannabis-DUI charging as a continuing and substantial caseload. See ACLU disparity page.

Comparison to Per Se States

South Carolina’s impairment-only framework places it in the same broad category as Massachusetts, New York, New Jersey, and most other East Coast jurisdictions; per se thresholds dominate in the West and Mountain regions. The principal practical difference is that per se states give both prosecution and defense a numeric anchor; impairment-only states require a fact-intensive jury inquiry into officer observations, SFST performance, and DRE evaluation. The defense bar in impairment-only states tends to focus on the unreliability of cannabis-DUI indicators developed for alcohol; the prosecution focuses on the totality of observable impairment.

Practical Guidance

• If stopped for suspected impaired driving: comply with the officer’s lawful instructions, but be aware that field sobriety tests are voluntary in many circumstances; the implied-consent statute applies to chemical testing (blood, breath, urine), not SFSTs.
• If arrested: contact a South Carolina criminal-defense attorney before discussing the underlying facts. Implied-consent refusal carries an administrative driver’s license suspension; refusal does not automatically defeat prosecution.
• If the cannabis was lawfully purchased out-of-state: this is not a defense to South Carolina DUI or possession charges. Out-of-state medical-cannabis cards are not honored.
• If federally regulated (DOT-certified driver, federal contractor, military, federally regulated transportation): a positive THC test triggers federal-employer adverse action regardless of SC outcome.
• If the conviction is a first offense: the Pretrial Intervention (PTI) program under §§ 17-22-10 ff. is broadly available for simple possession but generally not for DUI. See PTI page.