Little Brother and Dolores Umbridge

Dolores Umbridge is the plainest definition of "power abuse". After being given the title of head mistress she completely takes over and steals away many of the students rights. This is similar to the DHS in the way that they greatly abuse their power when they capture Marcus and his friends and harshly interrogate them after suspecting that they are terrorists. Umbridge abuses her power in an unjust way that eventually ends up with her being kicked out of Hogwarts.