Clearance Levels are used by S.H.I.E.L.D. to keep order in their system and protect information that is protected by S.H.I.E.L.D. Clearance levels both denoted the level of information an agent was allowed to have access to as well as their basic rank within S.H.I.E.L.D. An agent's clearance level is not based on how long they have been apart of the agency. If an agent dislikes their current position, they usually have the option to demote themselves in rank. There are 10 levels of clearance. When Phil Coulson became Director of S.H.I.E.L.D., he eliminated the clearance level system.