Your browser is unsupported

We recommend using the latest version of IE11, Edge, Chrome, Firefox or Safari.

Clarifying Drugged Driving Laws for Medical Cannabis Patients in Light of Budding THC Research

Since the Compassionate Use of Medical Cannabis Pilot Program Act (CUA) has been in effect, it has received various criticisms.[1] While a qualifying patient is now able to register and purchase cannabis in various forms to manage pain, fatigue, and appetite issues, qualifying patients also put themselves in a vulnerable legal predicament.[2] Besides risking employment termination with no viable legal recourse, patients also potentially face charges of drugged driving because the law has not caught up with science.[3]

Drugged driving is just as dangerous as drunk driving and in fact, drugged driving is on the rise.[4] Law enforcement has continued to struggle to determine which drugs impair drivers and at what doses.[5] Until more information is collected, registered patients of the CUA are left with little guidance regarding how to avoid being charged with drugged driving, especially given THC’s unique absorption patterns.

Registered patients are allowed to operate a motor vehicle with cannabis in their system, so long as they are not under the influence or impaired by it.[6] Under the influence of cannabis is defined as the presence of 5 nanograms or more of tetrahydrocannabinol concentrate in whole blood or 10 nanograms or more in any other bodily substance.[7] However, law enforcement continues to struggle with creating accurate, non-invasive testing for THC levels.[8] While alcohol-consumption is easily tested because the alcohol quickly permeates into the rest of the body, THC is fat soluble and is absorbed inconsistently, especially depending on how it’s consumed and how often.[9] Frequent cannabis users build up THC in their body fat, so a registered patient who uses cannabis daily could continue to leach the THC into other parts of their body, even after they have stopped using.[10] In theory, a registered patient who smokes cannabis heavily could stop ingesting cannabis for weeks and still test positive for a DUI under Illinois law.[11]

The result is that a registered patient who relies heavily on cannabis to manage their pain, fatigue, or appetite, is constantly at risk of being unable to pass a DUI urine or blood test. And besides the obvious legal ramifications both criminally and civilly, a patient can also get their medical card revoked for failing a DUI test or refusing to take a properly requested test.[12] Until scientific research more clearly pinpoints how cannabis effects operating a motor vehicle, the current law is an arbitrary threshold which endangers registered patients, legally consuming cannabis for medical purposes.

[1] Another major criticism of the CUA is explored by author Tyler Duffy in his analysis of workplace discrimination of medical cannabis with no legal recourse, under the CUA. Notably, because marijuana is still illegal federally, an employee’s termination in adherence with federal law, even though the employee is in compliance with state law, will likely be deemed legal. Therefore, the CUA does not protect medical cannabis patients from being terminated for legally using cannabis. Tyler Duffy, Article, Nip It In the Bud: Compassionate Use of Medical Cannabis Pilot Program Act Does Not Provide Employees A Legal Remedy for Adverse Action Based Upon Use in Compliance with the Statute, 49 J. Marshall L. Rev. 193, (2015).

[2] Id.

[3] Id.

[4] Mary Wisniewski, More police training, public education needed to stop ‘drugged’ driving: report, Chi. Trib., Apr. 26, 2017,

[5] Drug-Impaired Driving: Understanding the Problem & Ways to Reduce It, National Highway Traffic Safety Administration, (last visited Jul. 7, 2017),

[6] 410 ILCS 130/30(a)(3)(G)

[7] 625 ILCS 5/11-501.2(b-5)

[8] National Highway Traffic Safety Administration, supra note 5, 13.

[9] Angus Chen, Why Is It So Hard to Test Whether Drivers Are Stoned? NPR, Feb. 9, 2016,

[10] Id.

[11] Id.

[12] 410 ILCS 130/30(d)(f)