The obvious answer is for people who have and maintain a commercial driver's license (CDL). But there are other situations where a DOT medical card is required, even when a CDL is not.
From the Federal Motor Carrier Safety Administration (FMCSA):
Medical certification in accordance with FMCSA physical qualification standards is required when the driver is operating a commercial vehicle in interstate commerce that:
- Has a combined gross vehicle weight or weight rating of 10,0001 lbs. or more.
- Is designed or used to transport 9-15 passengers (including the driver) for compensation.
- Is designed or used to transport 16 or more passengers (including the driver) whether for compensation or not.
- Transports hazardous materials in quantities that require placarding under the hazardous materials regulations.
- When a driver returns from an illness or injury that interferes with driving ability, the driver must undergo a medical examination even if the medical examiner's certificate has not expired.
The medical examiner's certificate expires at midnight of the day, month, and year written on the certificate. There is no grace period on the expiration. The driver must be re-examined and recertified to continue to drive legally.
Other DOT medical card (CDL physical exam) requirements are posted as follows:
- DOT medical card: Blood Pressure
- DOT medical card: Vision
- CDL Hearing Requirements