A Maryland Physician's Certificate is a document issued by a licensed physician in the state of Maryland that certifies an individual is fit and able to perform certain activities. It is often required for certain types of employment, including those that involve driving, operating vehicles, or working with hazardous materials. There are three types of Maryland Physician's Certificates: 1. Class A Certificate: This is a certificate issued to a person who is fit and able to drive a commercial motor vehicle in interstate commerce. 2. Class B Certificate: This is a certificate issued to a person who is fit and able to drive a commercial motor vehicle in intrastate commerce. 3. Class C Certificate: This is a certificate issued to a person who is fit and able to drive a non-commercial motor vehicle in either interstate or intrastate commerce.