Two Shichibukai said: Crocodile, justice is made by the strong, and the weak are not qualified to talk about justice.

Doflamingo:

Are pirates evil? Navy is justice? This concept has been washed away countless times... Children who don't know what peace is and children who don't know what war is have completely different values! Only those who stand at the top can rewrite good and evil. This is neutrality here and now! Will justice inevitably prevail? ! Of course! Only the winner is righteous! ! !