Under the law, legal and illegal drugs are viewed very differently. One example that illustrates this is that while it is always illegal to be in possession of even small amounts of heroin, taking prescription drugs that are opiate-derivatives, like morphine or Oxycontin, is permitted as long as the user has a valid prescription from his or her doctor for the medication.
But when the individual with the prescription is a commercial motor vehicle operator, the issue becomes much murkier. There's a good reason for that.
Regardless of whether their original source was legitimate, many prescription drugs have side effects that can cause drivers to no longer be able to safely operate their vehicles. When those medicated drivers are behind the wheels of large, heavy semitrucks, the risks to others on the road with them rise significantly.
Even some nonprescription medications can cause drivers to be adversely affected and become safety hazards careening down the interstates at 70 mph or more. Over-the-counter (OTC) medicines — including the allergy and flu medicines Benadryl and Nyquil — can cause sleepiness and blurred vision, making it unsafe to drive after taking a prescribed dosage of the drugs.
Because of this, the commercial drivers' licenses of big rig truckers can be jeopardized by their otherwise very legal drug use for conditions like seasonal allergies, common colds and influenza.
Getting into a wreck with one of these large commercial trucks can be a deadly experience for passenger car operators and their passengers. If you suffered injuries in an accident with a semitruck driver, if it's suspected that he or she was under the influence of any incapacitating drug — legal or illegal — it could bolster your case for compensation for your injuries and other damages.
Source: Federal Motor Carrier Safety Administration, "Can a CMV driver be disqualified for using a legally prescribed drug?," accessed March 16, 2018