Military Police Brigade

The Military Police (憲兵団) is the most prestigious due to their work allowing them to live safely within the Inner Wall, abundant resources, and higher authority over other military sectors. However, in reality it is the most corrupted military sector due to a lack of oversight compared to the other sectors of the military. Due to their misuse of authority, the Military Police is also at odds with Garrison and especially with Scouting Legion. Only the top ten alumni from trainee squads can apply for the Military Police. However, according to the conversation between Hitch and Boris, there are other (illicit) ways to get in the sector such as fraternization, favoritism, etc.

Duty
The Military Police is the 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 3D gear and usually carry firearms instead. They are also in charge of tax collection and land distribution as seen in Ch. 15 when a couple policemen monitor farm production.

Structure
The Military Police is an organization with 2,000 members, with direct command over 3,000 additional personnel from the Garrison. This brings their total potential manpower to 5,000 soldiers. Their forces are divided between the major Districts, with 200 officers assigned per District.

Qualities
The Military Police is supposed to be an elite unit made of the most skilled soldiers due to its rigorous standards. The reality though, is a lazy, corrupt system that benefits from the powers granted to it. Though they are top ten graduates from the trainee squads; they are inexperienced since they only stay in the safety of Wall Sina and never engaged in battle with the Titans before.

The senior officers spend all their time gambling and drinking while leaving recruits to do all the work. They also pilfer taxes and misappropriate land as a recruit, Marlo, mentions in Ch. 31. This corruption is well-known with many people (even to Wall Sina citizens) criticizing their lack of care for anyone other than themselves. Refugees and forced laborers (called producers) hold simmering hostility against them.

However, many trainees still dream of joining the Military Police because it will allow them to live within Wall Sina and safety. Also, being so close to the center of human territory, most policemen have relatively little experience fighting Titans as compared to the Scouting Legion or the Stationary Guard. This, together with corruption, loose discipline, contempt from public, abuse of power makes this military branch the most incompetent out of the three.

However by Ch.45, it's revealed that the King becomes tougher on the Military Police for their lack of diligence in dealing with their corruption, lack of discipline, pilfering of taxes and mismanagement of lands. He orders them to leave the safety of Wall Sina and assist both the Scouting Legion and the Stationary Guards to look for the two other traitors in collaboration with Annie. By the end all three factions have banded together to help rescue Eren and Ymir from Reiner and Berthold.

In chapter 47 of the manga, all their shortcomings and negligence of trainings are brought to light; most personnel from Military police are all too easily slaughtered by titans even before the rescue operation began in earnest. In episode 24 of the anime, when a (Female)titan suddenly appeared in Wall Sina and went on a rampage that caused Wall Sina's terrified citizens to flee chaotically in all directions most (if not all) of military police personnel, afraid and completely at a loss of what to do, just stood transfixed and did nothing to alleviate the problem.