A doctor working for the administration?

I was looking at a site that said how pediatricians could work...such as group practice, hospital, college, company, etc. and one of the choices be government (state & local and federal).
How is it possible for a doctor to work for the federal/ state & local affairs of state? What would they do?A doctor working for the administration?
Federal prisons, VA hospitals, Public Health Service hospitals, military hospitals,Center for Disease Control.
all draw on doctors, thousands of them, and tens of thousands of nurses.
State prisons, police departments hire pathologists, local board of health,
Doctors who work at the VA Hospitals, work for the federal system.
They do the same entry as any other doctor; it's just that the organization is writing the salary checks.
You would hold a contract with the govt. when you finished academy. Some have tuition reimbursement, sign on bonus, etc. Make sure you read the fine print. Normally nation work at the military facility. There is also the VA hospitals. There are positions for Social security office for people applying for disability.