By law, who is ultimately responsible for ensuring the safety and road-worthiness of a CMV?

The most important aspect of traffic safety for yourself and others who share the road with you is that you personally inspect your vehicle. A vehicle defect found during an inspection could save you problems later. You could have a breakdown on the road that will cost you time and money, or even worse, an accident caused by the defect.
Federal and state laws require that drivers inspect their vehicles. Federal and state inspectors also may inspect your vehicles. If they judge a vehicle to be unsafe, they will put it out of service until it is repaired.