The most debated words ever uttered by a Jedi Master are: "A Jedi is not a creature of morals." This statement has unfortunately been translated, often by Jedi, to mean that a Jedi can do no wrong.
What it actually means is that Jedi are not enforcers of morality. While Jedi can bring or restore order and justice, they cannot themselves sit in judgment of others. There are two reasons for this.
First, the world is a vast place, full of cultures that no one Jedi can completely understand.
The second reason is that judgment can lead to vengeance. This is easy to understand, though not so easy to practice. Should a known murderer be allowed to go free? Should a man intent on murder be killed? To answer either question, a Jedi must first know the will of the Force. Neither decision can be made hastily, except where lives are threatened by inaction.
At the same time, while not judges, Jedi can be mediators. It is a role they are suited for, and one that works in accord to the Force since mediation leads to balance.