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Medical Marijuana, Employees Who Drive and the Risk of a DUI?

May 19, 2023

Reprinted with permission from the May 18, 2023 edition of The Legal Intelligencer © 2023 ALM Media Properties, LLC. Further duplication without permission is prohibited. All rights reserved.

Since the passage of The Pennsylvania Medical Marijuana Act (MMA), a top question of employers has been—what do we do with employees who use medical marijuana and who perform safety sensitive positions? Particularly, employers are often concerned about employees who drive as an essential function of their job—for example, employees at auto dealerships, outside sales people and project managers.

Section 510 of the MMA contains what has come to be known as “safety sensitive exceptions,” allowing employers to prohibit employees from performing certain safety sensitive jobs while under the influence of medical marijuana. For example, Section 510(3) states “a patient may be prohibited by an employer from performing any task which the employer deems life-threatening, to either the employee or any employees of the employer, while under the influence of medical marijuana.” Section 510(4) further states that “a patient may be prohibited by an employer from performing any duty which could result in a public health or safety risk while under the influence of medical marijuana.”

Arguably, either of these sections could apply to employees who drive a vehicle as part of their work duties. However, the question that has perplexed employers for years is – how do we define under the influence?

The Superior Court, last summer, and a Court of Common Pleas judge in Lancaster County, this winter, finally may have provided an answer. But, how far reaching is that answer?

In the summer of 2022, the Superior Court issued decisions in three criminal DUI cases—Commonwealth v. Dabney and Commonwealth v. Haney (published decisions) and Commonwealth v. Gordon (unpublished decision)—that caught the attention of employers with employees who drive. The Superior Court addressed whether Pennsylvania’s zero-tolerance DUI law includes an exception for drivers legally using marijuana under the MMA. In each case, the driver was stopped and questioned, the police officer established probable cause to administer a drug test, the test was positive for THC and the driver was charged with DUI. The drivers were certified to use medical marijuana in accordance with the MMA and argued that but for their medical use of marijuana, which was legal, they would not have tested positive for THC.

In analyzing whether an exception should be made to Pennsylvania’s DUI laws, when the driver claims to have only used medical marijuana, the courts first noted the language of the DUI statute. The relevant portion provides, “an individual may not drive, operate or be in actual physical control of the movement of a vehicle” when “there is in the individual’s blood any amount of a … Schedule I controlled substance” or a “metabolite” of a Schedule I controlled substance. 75 Pa. C.S. Section 3802(d)(1)(i), (iii). The court noted that all marijuana, medical or otherwise, is a Schedule I controlled substance under the Controlled Substances Act. Moreover, nothing in the MMA changed this classification.

Addressing the argument that the legalization of medical marijuana necessarily conflicts with the DUI statute, the Dabney court disagreed. The court referenced the actions specifically permitted by Act 16—growth, processing, manufacture, acquisition, transportation, sale, dispensing, distribution, possession and consumption of medical marijuana (in accordance with the act). Notably absent from the list of permissible actions was driving. In Gordon, while acknowledging that the decision “may lead to harsh consequences for patients with a valid medical marijuana prescription,” the Superior Court nonetheless upheld the DUI conviction noting that the DUI statute prohibits driving with marijuana metabolites in the blood, not the mere usage of medical marijuana. Finally, in Haney, the court reiterated that “driving after using medical marijuana, a Schedule I controlled substance, is not included in the ‘lawful use of medical marijuana’ under the MMA.” Accordingly, a driver convicted of DUI is “not denied any privilege solely for ‘lawful use of medical marijuana.’”

Naturally, when these decisions came out, the eyebrows of many employers were raised and the following question was posed—if a driver who legally uses medical marijuana can be found guilty of DUI if they have any level of marijuana metabolites in their system, how can we, in good conscious, allow an employee, who we know is using medical marijuana and who will test positive for marijuana metabolites, to drive a vehicle? If we allowed them to drive, wouldn’t we knowingly be allowing them to violate the law?

While these questions are logical and inherently reasonable, the answers weren’t exactly clear, because the Dabney, Gordon and Haney did not address the employment relationship or the safety sensitive exceptions in the MMA—they were criminal cases and a judge evaluating a claim for employment discrimination in violation of the MMA would not be bound by their holdings.

In January 2023, a Court of Common Pleas judge in Lancaster County extended the holdings of the DUI cases to a claim for employment discrimination in violation of the MMA. In the case of Clark v. J.R.K. Enterprises, Clark, a traffic flagger, was terminated when he advised his employer that he could not pass a drug test due to his use of medical marijuana each evening. The employer designated the traffic flagger position as safety sensitive and terminated Clark’s employment in accordance with Section 510 of the MMA, arguing that Clark’s admission that he would test positive for THC was an admission that he would be under the influence. In his holding, Judge Jeffrey Wright cited the challenges of using testing to determine impairment from cannabis and reasoned that to “construe ‘under the influence’ to mean anything other than having any amount of marijuana in a safety sensitive patient-employee’s system would be altogether unreasonable.” Wright utilized the decisions in DabneyGordon and Haney to support his holding. Wright noted “Dabney and Haney emphasize that for all the protections that the MMA provides to cardholders, the ‘lawful use’ of medical marijuana does not include driving after using medical marijuana. Lawful use of medical marijuana cannot, likewise, including dressing in safety gear, entering the roadway and directing drivers through precarious construction zones after using medical marijuana. Any other conclusion would be utterly irrational.” Further supporting his holding, Wright noted that the MMA’s “catch-all” safety sensitive exceptions (Section 510(3) and (4)) do not include definitions of under the influence.

Accordingly, he reasoned, by making a clear decision to omit a specific definition of under the influence, the General Assembly left employers to define the term. Without any scientific method to test or monitor for impairment, Wright found that it is reasonable that employers would define under the influence as it is defined in the DUI statutes—any amount of marijuana metabolites in the employee’s system.

So, what does all of this mean for employers who have employees in safety sensitive positions, specifically those who drive as part of their jobs? Simply, it means there is an argument—a compelling argument—to be made that employees who drive as part of their job may be prohibited from doing so if they are using medical marijuana, and either actually test positive or will test positive on a drug test. The reasoning? Driving is a task that an employer could deem to be “life-threatening,” and “under the influence” can mean having any amount of marijuana in the employee’s system. Accordingly, under Section 510(3) of the MMA, the employer can prohibit the employee from driving. While this argument is quite compelling in light of the DUI decisions and decision in Clark, a few notes of caution:

While an argument can be made, attorneys who advise employers should be mindful that the law remains unsettled in this space. Dabney, Gordon and Haney are criminal cases; the Clark decision is a Court of Common Pleas case. The decisions are not binding on the Commonwealth Court, the Superior Court or a federal court addressing the impact of Section 510 on a claim for discrimination under Act 16.

While the argument is strong for prohibiting an employee who utilizes medical marijuana from driving, due to the clear definition of “under the influence” in the DUI statutes, it unclear whether other courts will be persuaded by Wright’s argument for an extension of the rationale to other safety sensitive positions.

Employees who utilize medical marijuana necessarily have a serious health condition that would qualify as a disability. Accordingly, employers must consider whether the employee can perform the essential functions of the job with or without reasonable accommodation. Ignoring the employee’s use of medical marijuana may not be a reasonable accommodation, but that does not mean other accommodations shouldn’t be considered. For example, is there another job into which the employee can transfer or might a leave of absence be reasonable?

Finally, the language in 510 is that employers ‘may prohibit,’ not that they must prohibit. Moreover, because “under the influence” is not specifically defined, employers remain able to define it as something other than a positive drug test. Accordingly, if an employee is able to provide certification from their healthcare provider that off-duty use of medical marijuana will not cause them to be impaired or otherwise pose a risk to their safety or the safety of others while working, an employer may consider relying upon such certification and allowing the employee to consider performing their job.

The bottom line, as it is with all questions related to medical marijuana and its impact on the workplace, is that attorneys must stay up to date on the latest developments in the law and employers should be consulting with their counsel to make decisions that eliminate the risk of liability, that protect the safety of employees and the public and are respectful of the rights and privileges of their employees.

Denise Elliott is a labor and employment attorney with McNees Wallace & Nurick who frequently speaks and writes on the topic of medical marijuana in the workplace. She is a member of the Pennsylvania Chamber of Commerce Medical Marijuana Taskforce and routinely advises employers regarding the impact of marijuana legalization on drug testing and workplace safety policies. She can be reached at or 717-581-3713.


Denise E. Elliott

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