Raising a successful marijuana intoxication defense against an alleged work-related injury may have been complicated by recent legislation, but defendants can still make it a successful defense if they remember the finer points of proving proximate cause.
Recreational use of marijuana in California became legal for adults 21 and older on Nov.9, 2016, when Proposition 64 (Adult Use of Marijuana Act) was approved by voters.
Even though recreational and medicinal marijuana use is legal under California state law, it remains illegal under federal law.
When raising an intoxication defense against an alleged work-related injury, the applicable statute, LC 3600(a)(4), specifically references the “unlawful use of a controlled substance.” This clearly applies to marijuana.
Courts have had to grapple with how to apply the “unlawful use” language to marijuana. In practice, the focus tends to remain on the employer’s ability to prove the two core elements: intoxication and proximate cause.
The legality of recreational and medical marijuana in California does not invalidate an otherwise successful intoxication defense. Because marijuana remains illegal under federal law, California courts have affirmed that employers may still terminate or discipline employees (and successfully defend a WC claim) for using marijuana in violation of a drug-free workplace policy.
KEY POINTS OF AN INTOXICATION DEFENSE
1. The Burden of Proof is on the Defense
Defendants must prove two critical elements by a preponderance of the evidence:
- Employee was intoxicated at the time of the injury.
- Intoxication was the “proximate cause” of the injury.
2. Proving Marijuana Intoxication is Difficult
A positive THC test is generally not enough on its own to prove intoxication or impairment at the time of injury, especially with marijuana.
Here are some reasons why:
- THC lingers: Unlike alcohol, THC (the psychoactive component of pot) can remain detectable days or weeks after intoxicating effects have worn off. A positive test only proves past use, not impairment at the time of the accident.
- Need for corroborating evidence: To prove actual intoxication, the defense typically needs to provide additional evidence, such as:
- Witness testimony regarding the employee’s behavior (slurred speech, poor coordination, impaired judgment) just before the injury.
- Medical evidence from an expert, like a toxicologist, demonstrating that the level of THC found would have caused psychomotor impairment or significantly affected the employee’s judgment at the time of the injury.
3. Impacts of AB 2188 on Proving Proximate Causation
Proving that the marijuana use was the proximate cause of the work-related injury is an essential part of a intoxication defense. However, this was complicated by Assembly Bill 2188, which took effect on 1/1/24.
While not a court decision, AB 2188 will strongly influence future WCAB cases.
- Effect: It generally prohibits employers from discriminating against an employee based on a drug test that detects non-psychoactive cannabis metabolites (the inert byproduct of past use).
- Implications for workers’ compensation: If the defense cannot use a standard urine drug screen to justify termination due to off-duty use, it further weakens the already tenuous argument that a positive urine test alone proves active intoxication and causation for workers’ compensation. Defendant’s focus will now be forced to rely on more costly and difficult-to-obtain evidence, like:
- Testing for active THC (often via blood or oral fluid).
- Extensive witness statements detailing visible impairment (stumbling, slurred speech, confusion).
- Toxicology experts to connect the THC level to the injury.
4. Proving Proximate Causation Can Still Be Done
Although the intoxication defense is difficult to successfully employ, here are some fact patterns with a “high” (pun intended) likelihood of success:
Example #1: Construction worker falls from a low wall while walking across a job site. Witnesses testify employee was staggering, smelled of marijuana, and was “acting confused” just prior to the fall. A high level of active THC (parent compound in a post-accident blood test), combined with witness testimony, will likely be found to demonstrate that intoxication was the proximate cause of the fall
Example #2: Employee’s post-injury actions confirm an effort to hide impairment. After a slip-and-fall, employee refuses immediate emergency medical care on-site, stating they don’t want to be drug tested because they smoked marijuana that morning. This admission (an exception to the hearsay rule), corroborated by the circumstances of the injury (a simple slip on flat ground), is evidence linking the self-admitted intoxication to the cause of the injury.
TAKEAWAYS
Got a positive marijuana test? It, like any other intoxication defense, is difficult to prove without scientific evidence and testimony, some of which hopefully comes from a toxicologist and/or other medical expert.
Don’t forget to:
- Prove intoxication
- Prove proximate cause
- Pass the chips (munchies anyone?)
Don R. Barthel is one of the founding partners of Bradford and Barthel, and is based in the firm’s Sacramento office. He has taken thousands of doctor depositions and is an expert on the AMA Guides to the Evaluation of Permanent Impairment. If you have any questions about workers’ compensation defense issues, please feel free to contact him at dbarthel@bradfordbarthel.com or at (818) 654-0411.
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