With legalization and decriminalization of marijuana, and medical marijuana laws sweeping the country, police are stepping up enforcement of driving while impaired by drugs and controlled dangerous substances enforcement. In Maryland, these offenses are contained in Transportation Article, § 21-902(c) driving while impaired by drugs or drugs and alcohol to the extent that the driver is unable to drive safely and § 21-902(d) driving while under the influence of a controlled dangerous substance. The penalties can be up to 60 days in jail and/or a $500 fine and 8 points at the Motor Vehicle Administration (MVA) for the § 21-902(c) offense and up to one year and/or a $1000 fine and 12 points at the MVA for the § 21-902(d) offense.
In the typical DUI drugs case, the police officer stops a vehicle for erratic driving and detects some impairment in the driver. Breath testing excludes alcohol as a cause of the impairment and the officer calls in a specially trained officer called a Drug Recognition Expert. After performing a series of tests the DRE directs medical personnel to withdraw blood for testing at the State Police crime lab in Pikesville, Maryland. While the validity of the science of the so-called DREs is being litigated (see Drug Recognition Expert (DRE) Protocol is Junk Science Says Carroll County Circuit Court) Maryland law requires that only a DRE can request, require or direct a blood test to determine if any drugs are in the blood. This is an explicit requirement of Transportation Article, § 16-205.1(i)(2).
When the blood gets to Pikesville, the State Police crime lab does not test for THC or hydroxy THC, the psycho-active drug and its metabolite that are in the blood of a person who is high. Rather, the lab only tests (with respect to marijuana) for carboxy THC. This is a metabolite that can be present in the body for up to 30 days after using marijuana. As a result, the scientific consensus is that the presence of carboxy THC alone in the blood does not prove that a person is impaired by marijuana at the time of testing. For example, the Supreme Court of Arizona said last April in the case of State ex rel Montgomery v. Harris,
Because Carboxy-THC can remain in the body for as many as twenty-eight to thirty days after ingestion, the State's position suggests that a medical-marijuana user could face prosecution for driving any time nearly a month after they had legally ingested marijuana. Such a prohibition would apply even when the driver had no impairing substance in his or her body and notwithstanding the State's ability to test both for THC, the primary substance that causes impairment, and Hydroxy-THC, the metabolite capable of causing impairment.