As more states across the country move to legalize marijuana for medical and recreational use, questions are being raised about how legalization impacts road safety—especially when it comes to impaired driving. While marijuana use is now legal in many places, driving under the influence of any impairing substance remains against the law. Still, the growing availability of cannabis products has added a layer of complexity to DUI enforcement and personal injury claims.
For people injured in motor vehicle accidents, understanding how marijuana legalization affects liability and compensation is more important than ever. Proving impairment, understanding evolving state laws, and navigating insurance claims can all be more difficult in the context of legal marijuana use.
In this article, we’ll look at how marijuana legalization is impacting DUI crashes, what it means for liability in personal injury cases, and what to do if you're hurt in a collision involving a driver who may have been impaired by cannabis.
Marijuana and Impaired Driving: What the Research Shows
Studies have shown that marijuana can impair coordination, reaction time, and judgment—all of which are essential for safe driving. According to the National Highway Traffic Safety Administration (NHTSA), THC—the psychoactive component in marijuana—can negatively affect a driver’s ability to operate a vehicle safely.
However, proving marijuana impairment is far more complicated than testing for alcohol. Unlike alcohol, THC can remain in a person’s system for days or even weeks after use, meaning a positive test result doesn’t always indicate current impairment. This makes enforcement and legal cases more challenging.
DUI Laws and Marijuana
Even in states where marijuana is legal, it is still illegal to drive while impaired by it. Most states have laws that prohibit operating a vehicle while under the influence of any drug that impairs driving ability—legal or not.
Per Se Laws
Some states have adopted “per se” laws for marijuana, which set a legal limit for the amount of THC in a driver's blood (similar to the 0.08% BAC standard for alcohol). However, these laws are controversial and not universally adopted because THC affects individuals differently and doesn’t correlate neatly with impairment.
Zero-Tolerance Laws
Other states have taken a zero-tolerance approach, where any detectable level of THC or its metabolites in the driver's system can lead to a DUI charge. This can raise questions in personal injury cases where someone is injured by a driver who used marijuana but may not have been actively impaired at the time.
Field Sobriety Tests and Drug Recognition Experts (DREs)
Because marijuana impairment is harder to measure with a breathalyzer, officers often rely on behavioral cues, field sobriety tests, and evaluations by trained Drug Recognition Experts. However, these assessments are subjective and can be contested.
Liability in Marijuana-Related DUI Accidents
In personal injury law, liability generally depends on proving negligence. If a driver was impaired by marijuana and caused an accident, that impairment could be a key factor in establishing negligence.
Evidence in Personal Injury Claims
When marijuana use is suspected, evidence might include:
- Police reports and witness statements
- Drug test results (if available)
- Observations from responding officers
- Traffic or surveillance camera footage
- The driver’s admission or behavior at the scene
Even if the driver was not criminally charged or convicted of DUI, civil liability can still apply. Personal injury cases use a lower burden of proof than criminal cases, meaning a driver can be held financially responsible even without a criminal conviction.
Challenges in Proving Impairment and Liability
Because of the complexities around marijuana impairment, victims of crashes involving cannabis use may face additional hurdles when pursuing a claim. Insurance companies may argue that the driver wasn’t impaired, or that the marijuana in their system had no effect on the crash.
This is why working with a personal injury attorney who understands how marijuana DUI cases work is important. An experienced lawyer can help gather the right evidence, consult expert witnesses if needed, and build a case that shows how impairment contributed to the accident.
What to Do If You’re Involved in an Accident with a Potentially Impaired Driver
If you suspect the other driver in a crash may have been under the influence of marijuana:
- Call the police immediately so the incident is officially documented.
- Share your suspicions with the responding officer, including any behavior you noticed (e.g., red eyes, confusion, unusual speech).
- Seek medical attention and keep records of your injuries.
- Take photos of the vehicles, surroundings, and any visible evidence (like cannabis paraphernalia).
- Contact a personal injury lawyer as soon as you possibly can to ensure you protect your right to seek compensation.
Call Brandon J. Broderick For Legal Help
As marijuana laws continue to evolve, so do the challenges that come with personal injury claims involving impaired drivers. If you’ve been injured in an accident and suspect marijuana use played a role, don’t navigate the process alone.
At Brandon J. Broderick, Attorney at Law, we understand the unique issues that come with these types of cases. From investigating the crash to dealing with insurance and building a strong legal claim, we’re here to fight for the compensation you deserve.
Contact us today for a free consultation.