No lah, procedures is this:
Unit caught someone inside camp doing something illegal or charging
him etc,
contact the MP of the brigade, they come and take him to military
court based in brigade.
DB etc if found guilty.
Consider them the prison guards only.
Sometimes do investigations also, on ongoing cases.
They DO NOT ACTIVELY catch people outside camp, like what without
proper uniforms or what, they only catch them if needed or if they
HAPPEN to wear their MP uniform. 
