Understanding What Regulations Apply and How To Uncover Hidden Evidence After a Serious Crash
By Attorney Brian T. Mohs
Partner, Fried Goldberg, LLC

When a commercial truck is involved in a serious or fatal crash, the cause isn’t always immediately clear. But in some cases, drug or alcohol use may be a contributing factor, and the legal implications are significant. Truck drivers are held to strict federal regulations regarding substance use, and when those rules are broken, lives are often at risk.
If you're a truck accident lawyer building a case for an injured client, understanding the regulations and knowing how to uncover evidence of substance use can make or break the claim. At Fried Goldberg LLC, our attorneys are often called in to consult on these high-stakes cases. We know the federal rules inside and out and can help you identify where liability may be hiding.
Federal Rules Prohibit Driving Under the Influence
Under federal law, drivers of commercial motor vehicles (CMVs) are strictly prohibited from using or being under the influence of drugs or alcohol while on duty. That includes not only illegal substances but also certain prescription drugs that may impair driving ability. The rules apply to anyone operating a commercial vehicle that meets certain size, weight, or passenger criteria, not just CDL holders.
More specifically, drivers may not:
- Use or be under the influence of alcohol within four hours of going on duty.
- Use alcohol while operating a CMV.
- Use, possess, or be under the influence of Schedule I drugs, amphetamines, narcotics, or any substance that affects safe operation.
Motor carriers are also forbidden from permitting or requiring drivers to violate these rules. This creates potential liability for the company, especially if it failed to conduct proper drug or alcohol testing or ignores warning signs.
When Is Drug or Alcohol Testing Required After a Crash?
One of the most common misconceptions is that drug or alcohol testing is always required after a crash involving a commercial truck. In reality, testing is only mandated under certain conditions and only for CDL drivers.
Testing is required when:
- The crash involves a fatality.
- The driver receives a citation, and the crash involves either bodily injury requiring immediate treatment or disabling vehicle damage.
Timing is also critical. Alcohol tests must be performed within eight hours, and drug tests within 32 hours. If a test isn’t completed in time, the motor carrier must document the reason. That’s why it's important to act fast in the early stages of a case.
Why Many Motor Carriers Don’t Test, and How to Fight Back
It’s not uncommon for motor carriers to claim they couldn’t get a driver tested because the crash happened at night or in a remote location. That excuse doesn’t hold much weight if there were testing centers nearby. A simple online search can help you identify facilities close to the crash site that were open and available, which can then be used to impeach the carrier's explanation during deposition.
You should also send a preservation of evidence letter immediately upon taking the case. That letter should request all pre-employment, post-accident, random, and reasonable suspicion drug and alcohol test results. If the carrier refuses to provide them, you may need to file suit and obtain them through discovery.
Don't Overlook Prescription Drugs
Just because a driver has a valid prescription doesn’t mean they’re cleared to operate a commercial vehicle. Certain medications are automatically disqualifying. Others require a certified medical examiner to affirm that the substance won’t interfere with safe driving.
As part of the driver qualification process, operators are required to disclose all medications during their physical exam and on the Medical Examination Report (Form MCSA-5875). If a driver failed to disclose medications or if the medication should have disqualified them, that’s a potential avenue of liability.
Ask the driver during deposition what prescription drugs they were taking at the time of the crash. Compare those answers to what they disclosed on their long-form medical report. If there’s a conflict or if the drug appears on a disqualifying schedule under 21 C.F.R. Part 1308, you may have a stronger claim.
Disqualification Based on Prior Offenses
Federal regulations also disqualify drivers who have:
- Driven under the influence with a BAC of 0.04 or higher.
- Refused a required drug or alcohol test.
- Driven under the influence of narcotics, amphetamines, or other disqualifying substances.
Disqualification periods range from one to three years, depending on whether the driver had prior offenses. If your investigation reveals that the driver should have been disqualified at the time of the crash, that can strengthen your case significantly.
Fried Goldberg LLC Helps You Build a Stronger Case
At Fried Goldberg LLC, our attorneys have litigated hundreds of truck accident cases involving violations of federal safety rules. We don’t just look at the crash. We dig deeper to uncover whether the driver was qualified, whether the motor carrier followed protocol, and whether drug or alcohol use may have contributed to the incident.
Our firm is nationally recognized for handling high-stakes trucking litigation. We understand the complex medical, legal, and regulatory aspects involved in these cases and have the resources to uncover what others might overlook.
If you’re litigating a serious truck crash and suspect substance use may be a factor, we’re here to help you develop a winning strategy. Let’s talk about how we can support your case. Contact Fried Goldberg LLC today to get started.
"Most people know that Fried Goldberg is the top tractor-trailer litigation firm in the southeast. However, they are also the most generous. They share their knowledge willingly on a regular basis with anyone who cares to learn from them. ...Can't say enough about this group." - John F., ⭐⭐⭐⭐⭐