The Dark Arts and the Legal System

Do you think like in a real world where bad people do bad things and then lie about them that you need to use some dark arts to get to the truth sometimes? I just can never get behind that because i feel like it sullies the entire system. It's unrealistic to expect this sort of goody two shoes fairs fair approach, he says. "When you're dealing with bad people sometimes a bit of tricking them can get you to them"