Authority is give by those under authority.

If you find your boss/supervisor/even yourself has to always remind people they/you have the authority, then you/they have no authority!

Never follow someone who does this because they don't know how to lead!

 People with authority never need to say they have authority; in fact, everyone knows and respects that this person has authority. After all, the authority was give by those who obey the one with authority.