Case By Case
This means each aspect of the situation is being considered individually before reaching any conclusion.
Eye For An Eye
This is an idiom used to tell that if you do something wrong, the judiciary will punish you very badly. Usually its used in Arab countries where if some one makes a person blind then criminal’s eye is also removed.
Judge, Jury And Executioner
When someone has the overall authority to take decision and can do whatever he/she wishes we use this idiom.