Two reasons for the above given statement is as follows:

(a) First and most important point is that in a criminal justice system the police and the judges are on one side and the public prosecutor and the defense lawyers on the other.

This method helps in keeping the balance between two sides of the judicial edifice. Also this ensures an impartial and fair justice.

(b) If all the duties are given to a single person then this leads to the end of the democratic system.