Which document must a CDL holder carry while operating a commercial vehicle?

A CDL holder is required to carry a valid commercial driver's license (CDL) along with a medical certification while operating a commercial vehicle. The CDL confirms that the driver has passed the necessary tests and is authorized to operate specific types of commercial vehicles. The medical certification ensures that the driver meets the health standards necessary for safely operating a commercial vehicle, verifying that they do not have any medical conditions that would impair their ability to drive.

This requirement is in place to enhance road safety and ensure that commercial drivers are both legally authorized and fit to operate larger, potentially more dangerous vehicles. Other documents, such as insurance papers and registration documents, while important for various reasons, do not provide the direct proof of both licensing and medical fitness that are critical for commercial driving.