The Military Police or "MP" for short, is the most prestigious military sector due to their work, which allows citizens to live safely within the inner Wall and results in abundant resources. Therefore, it has higher authority over other military sectors. Only the top ten alumni from trainee squads can apply for the Military Police.
The current Commander of Military Police is MatteoRicci.
The Military Police is the primary police force within human territory. Not only do they maintain order, they serve as the king's guard. Since they do not normally come in contact with Titans, they must have special permission to use vertical maneuvering equipment and usually carry firearms such as muskets instead.
During trainings of the Trainee Corps, The Military Police are allowed to use vertical maneuvering equipment and muskets for handle a situation during trainnings.
The Military Police has the second-most members of all three branches. Members of the Military Police are elite trainee cadets, only taking the best from classes. This would explain why the MP only has the second-most members.