Driving under the influence of illicit substances has always been illegal in Maryland, but with marijuana recently decriminalized, driving while high has become more frequent according to data from the state – and potentially harder to catch.
In 2023, after the legalization of marijuana in July, reports of driving under the influence of cannabis (DUIC) spiked by more than 20%, according to the Maryland Cannabis Administration’s 2024 Maryland Medical Cannabis Patient Survey. The administration defined DUIC as driving while consuming or within three hours of consuming cannabis. Last year those reports leveled out with a 5% drop in respondents who said they had driven under the influence at least once in the month before the survey.
According to the MCA’s 2025 Maryland Cannabis Use Biannual Study, drug-impaired driving arrests have dropped over 70% in the past seven years – not specifying arrests due to cannabis impairment. However, cannabis-positive DRE evaluations accounted for about 25% of all evaluations in 2023 according to the study.
Unlike other states that have zero-tolerance or legal limit laws – Maryland has no state law specifying how long drivers should wait before getting behind the wheel nor any legal threshold for acceptable THC levels. The MCA’s resources point to a 2017 study suggesting drivers should wait at least six hours after consumption due to potential delayed effects and impairment.
There are currently no cannabis breathalyzer tests like those available for alcohol screening. Efforts to create a breathalyzer have largely failed, because “the THC molecule is much bigger than ethanol and its behavior after ingestion is very different from alcohol,” Dr. Guohua Li, professor of epidemiology and the founding director of the Center for Injury Science and Prevention at Columbia University, said in an interview with The Journalist’s Resource…