South Carolina DUI Laws Target Marijuana Impairment Despite Absence of Standardized Breathalyzer Testing Measures

South Carolina treats marijuana DUI like alcohol, but without breath tests, officers rely on behavior and odor to make arrests. Learn the legal risks here.

By: AXL Media

Published: Mar 6, 2026, 8:24 AM EST

Source: The information in this article was sourced from The State

Equal Legal Standing for Substance Impairment

South Carolina state law draws no distinction between the consumption of alcohol and the use of marijuana when it pertains to operating a motor vehicle. According to the Shealey law firm, the existing DUI statutes are applied universally to any substance that compromises a driver’s ability to safely navigate the roads. This means that motorists suspected of being under the influence of cannabis face the same immediate risk of arrest as those suspected of drunk driving, provided a law enforcement officer establishes probable cause during a traffic stop.

The Subjective Nature of Roadside Detection

A significant divergence exists between alcohol and cannabis enforcement due to the current limitations of forensic technology. While a blood alcohol concentration of 0.08% serves as a definitive legal threshold in breath tests, no such standardized biological metric exists for active THC impairment in the field. Consequently, law enforcement officials must rely on a constellation of behavioral indicators, including erratic speed changes, slurred speech, and bloodshot eyes. The Shealey firm notes that without a mechanical test, officers are often forced to make a professional guess based on their training in drug detection protocols.

Legislative Friction Over Probable Cause Indicators

The reliance on sensory evidence has sparked a debate within the state’s political corridors regarding the validity of certain investigative triggers. There is currently a bill pending in the General Assembly that seeks to restrict the ability of officers to use the smell of marijuana as a sole determination for establishing driver impairment. This legislative move highlights the ongoing tension between traditional policing methods and the scientific difficulty of proving real-time intoxication, as the presence of an odor does not always correlate with the immediate inability to operate a vehicle.