Medical Marijuana in Ohio: A Choice Between Treatment and Independence

Photo by Richard T on Unsplash

Silver Flight, Associate Member, University of Cincinnati Law Review

I. Introduction

In June 2016, Ohio legalized medical marijuana[1] for qualifying medical conditions, including,

“AIDS, amyotrophic lateral sclerosis, Alzheimer’s disease, cachexia, cancer, chronic traumatic encephalopathy, Crohn’s disease, epilepsy or another seizure disorder, fibromyalgia, glaucoma, hepatitis C, Huntington’s disease, inflammatory bowel disease, multiple sclerosis, pain that is either chronic and severe or intractable, Parkinson’s disease, positive status for HIV, post-traumatic stress disorder, sickle cell anemia, Spasticity, spinal cord disease or injury, terminal illness, Tourette syndrome, traumatic brain injury, and ulcerative colitis.”[2]

Ohio residents who have a qualifying condition can “get a medical marijuana recommendation and register for a marijuana card,”[3] allowing them to legally consume medical marijuana.

However, under Ohio Revised Code § 4511.19, it is illegal to operate a vehicle with a blood concentration of 2 ng/ml of marijuana (referring to THC, or delta-9-tetrahydrocannabinol, the main psychoactive component of marijuana), 50 ng/ml of marijuana metabolite, or 5 ng/ml of metabolite in combination with other drugs. Or, if a urine test is used, the limit is 10 ng/ml of marijuana, 35 ng/ml or marijuana metabolite, or 15 ng/ml of metabolite in combination with other drugs.[4]

These per se limits raise concerns for medical marijuana users because marijuana and its metabolites can show up in blood or urine tests days or weeks after it has been used. Additionally, these test results do not accurately reflect driving impairment.[5] In fact, studies have shown that “the level of THC in the blood and the degree of impairment do not appear to be closely related.”[6] This post will address how marijuana affects driving ability, our current methods of testing for marijuana use or impairment, the limitations of such testing, and what steps need to be taken so that medical marijuana users do not have to choose between treatment and independence.

II. Marijuana and Driving

Studies are mixed on how marijuana affects driving. A 2012 study found that “[c]annabis smoking increases lane weaving and impaired cognitive function” such as “reaction times, divided-attention tasks, and lane-position variability,” and the effect was worse when combined with alcohol.[7] A 2014 study found that “[i]n Colorado, the proportion of drivers in a fatal motor vehicle crash who were marijuana-positive was . . . 5.9% in the first 6 months of 2009, and 10% at the end of 2011,”[8] where medical marijuana was legalized in 2000.[9]

The National Highway Traffic Safety Administration (NHTSA) reported in 2015 that studies showed that those who took marijuana drove slower, used greater following distances, and took “fewer risks than when sober,” in contrast to subjects who had alcohol, who “typically [drove] faster, follow[ed] at closer distances, and [took] greater risks.”[10] Although those who drove while impaired by marijuana attempted to self-correct by driving more safely, NHTSA did not believe this would be effective, writing, “[g]iven the large variety of driving related skills that are affected by THC, especially cognitive performance and judgment, the attempt by drivers who have ingested marijuana to compensate for the effects of marijuana is not likely to mitigate the detrimental effects on driving related skills.”[11]

III. Marijuana and Testing

After alcohol, marijuana “is the primary drug detected in the US drugged driving cases and fatal motor vehicle crashes.”[12] However, “this statistic may be misleading due to the very marked persistence of THC in the body after consumption that is not necessarily reflective of impairment.”[13] The NHTSA report stated that “there are currently no evidence-based methods to detect marijuana-impaired driving”[14] and that marijuana’s reported effects on driving can also be caused “by alcohol, other drugs and driver conditions and activities like distraction, drowsiness, and illness.”[15] Additionally, the report stated that “the poor correlation of THC level in the blood or oral fluid with impairment precludes using THC blood or oral fluid levels as an indicator of driver impairment.”[16] Urine testing was also not useful.[17]

Instead, NHTSA’s suggestion was to train officers to recognize signs of drug impairment and have them document their observations as evidence, saying that “[t]he lack of toxicological evidence simply means that the officer has to offer other evidence that the driver was under the influence of marijuana and too impaired to drive safely.”[18] However, the report also noted that “[i]t is not possible to predict whether there might be a unique combination of cues that could be used by law enforcement to detect marijuana-impaired driving with a high degree of accuracy.”[19] Therefore, it would still be a very subjective test by law enforcement and susceptible to false positives.

More research is needed to find ways to objectively test for marijuana impairment. Currently, there is a breathalyzer in development that would be able to detect if someone had smoked marijuana recently, but as of now, this is the only device capable of distinguishing recent marijuana use from use within the past week or month.[20] Some states are moving toward collecting oral fluid rather than blood, which would be less invasive and allow roadside tests to be conducted more quickly than waiting to transfer a suspect to a lab for a blood test.[21] However, while the saliva test may be easier to administer, it still runs into problems with the inability to test whether the driver is actually impaired by THC.

IV. State DUI Laws

Regarding per se laws like Ohio’s that limit the amount of permissible THC concentration in a suspect’s blood, the NHTSA report stated “[t]his per se limit appears to have been based on something other than scientific evidence.”[22] As of September 2021, five states have per se limits for THC, ranging from 2-5 ng/ml, while twelve states have zero-tolerance laws.[23] If a driver tests past these limits, they can automatically be charged with a DUI even if they were not actually impaired.

In 2015, before medical marijuana had been legalized in Ohio, a plaintiff charged with an OVI based on marijuana and alcohol use attempted to challenge Ohio’s per se law in the 10th District Court of Appeals.[24] However, the court held that the statute was not unconstitutionally vague, even though “the quantity, method, or timing of marijuana consumption needed to achieve metabolite levels violating the statute will vary from person to person,”[25] and noted that the plaintiff had “presented no expert testimony to rebut the legislature’s articulated and supported conclusion that marijuana use results in impaired driving and metabolites reflect and impairing level of marijuana use by the person testing at or above the statutory threshold.”[26]

In contrast, the majority of states require the driver to be under the influence of, or affected by, THC to be convicted of a DUI.[27] In Colorado, a blood test showing 5 ng/ml of THC creates a “permissible inference that the defendant was under the influence of one or more drugs,”[28] but a driver who is charged can introduce an affirmative defense that they were not impaired.[29] This type of balanced approach may be more useful until more objective testing measures are available.

V. Conclusion

More research is needed to find ways to test for recent marijuana use and whether a driver is actually impaired. In the meantime, however, it is clear that Ohio’s per se law is not based on scientific evidence and forces individuals to make a choice between taking medical marijuana or being able to drive, even days or weeks after consumption. Because levels of THC or its metabolites in the body do not indicate levels of impairment, this kind of limit is not useful to distinguish those who are driving while impaired from those who used medical marijuana responsibly and are not currently impaired.

Law enforcement and legislators need to understand that marijuana cannot be tested for in the same way as alcohol, because it is a different drug and behaves differently in the body. While waiting for scientific advances and the release of the marijuana breathalyzer, Ohio should, at a minimum, follow the trend of other states and require that the driver show signs that they are under the influence of one or more drugs before they can be convicted of a DUI. This would make it easier and safer for patients to use medical marijuana responsibly and not risk a DUI every time they drive.

[1] Ohio HB 523 Signed Into Law, Ohio Medical Marijuana Control Program (June 8, 2016)

[2] Frequently Asked Questions, Ohio Medical Marijuana Control Program, (last visited Nov. 14, 2021).

[3] How To Get an Ohio Marijuana Card, Ohio Marijuana Card, (last visited Nov. 14, 2021).

[4] Ohio Rev. Code Ann. § 4511.16.

[5] Godfrey D. Pearlson, Michael C. Stevens & Deepak Cyril D’Souza, Cannabis and Driving, 12 Frontiers in Psychiatry 1, 2 (2021).

[6] Richard P. Compton, Nati’l Highway Traffic Safety Admin., DOT HS 812 440, Marijuana-Impaired Driving — A Report to Congress 7 (2017).

[7] Rebecca L Hartman & Marilyn A Huestis, Cannabis Effects on Driving Skills, 59 Clinical Chemistry 478, 478 (2013); see also David Migoya, Are You High? The Science of Testing for Marijuana Impairment is Hazy, and Evolving, The Denver Post (Aug. 25, 2017),

[8] Stacy Salomonsen-Sautel, Sung-Joon Min, Joseph T. Sakai, Christian Thurstone & Christian Hopfer, Trends in Fatal Motor Vehicle Crashes Before and After Marijuana Commercialization in Colorado, 140 Drug & Alcohol Dependence 137, 139 (2014); Migoya, supra note 7.

[9] Salomonsen-Sautel et al., supra note 8, at 137.

[10] Compton, supra note 6, at 12.

[11] Id.

[12] Godfrey D. Pearlson, Michael C. Stevens & Deepak Cyril D’Souza, Cannabis and Driving, 12 Frontiers Psychiatry 1, 2 (2021).

[13] Id.; see also David S. Fink et al., Medical Marijuana Laws and Driving Under the Influence of Marijuana and Alcohol, 115 Addiction 1944, 1949 (2020) (“Given that THC concentrations in oral and blood tests remain detectible long after exposure, the rise in the prevalence of weekend nighttime drivers testing positive for THC is indicative of overall increases in cannabis use, rather than direct estimates of DUIC prevalence”).

[14] Compton, supra note 6, at 13.

[15] Id. at 13.

[16] Id. at 27.

[17] Id. at 10.

[18] Id. at 28.

[19] Id. at 13.

[20] Marijuana Breathalyzer | One-of-a-Kind Technology, Hound Labs, (last visited Nov. 14, 2021).

[21] Samantha Bloch, States Explore Oral Fluid Testing to Combat Impaired Driving, Nat’l Conf. State Legislatures (May 10, 2021),

[22] Compton, supra note 6, at 28.

[23] Drugged Driving | Marijuana-Impaired Driving, Nat’l Conf. State Legislatures (last visited Nov. 14, 2021).

[24] State v. Topolosky, 2015-Ohio-4963.

[25] Id. ¶ 28.

[26] Id. ¶ 34. For a case in another per se state, see City of Kent v. Cobb, 196 Wash. App. 1043 (2016) (holding that a similar per se law in Washington was also not unconstitutionally vague). For cases in zero-tolerance states, see Commonwealth v. Murphy, 239 A.3d 96 (Pa. Super. Ct. 2020), appeal denied, 258 A.3d 406 (Pa. 2021) (holding that appellant could be convicted of a DUI after a blood test revealed minimal amounts of marijuana metabolite, despite the fact that there was no indication that his marijuana use was recent or illegal);  Dobson v. McClennen, 238 Ariz. 389, 393 (2015) (holding that those with a medical marijuana card could assert an affirmative defense to a DUI that the concentration of marijuana or its metabolites in their blood was insufficient to cause impairment, despite the lack of a commonly accepted threshold for identifying impairment).

[27] Id. (showing that 32 states and 6 territories have this policy); State Drugged Driving Laws, NORML (last visited Nov. 14, 2021).

[28] Colo. Rev. Stat. Ann. § 42-4-1301.

[29] Drugged Driving | Marijuana-Impaired Driving, Nat’l Conf. State Legislatures (last visited Nov. 14, 2021).


  • Silver is a JD/MA dual-degree student in law and women's, gender, and sexuality studies, with a background in violin performance and pedagogy. Their MA research is on gender identity and gender markers on IDs, and on Law Review they wrote about related topics such as name change procedures, anti-transgender legislation, and how gender identity is being addressed in Equal Protection law.

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