Jewish tradition dedicates a significant effort to define Jewish Ethics, and yet comparatively little to the Ethics of Power because between the year 70 CE and 1948 Jews did not have much power issues to worry about. Let's try then to extrapolate from what we know about Jewish tradition and Jewish culture.
During the Passover Seder we tell the story of the Exodus, and when we recall the ten plagues we use drops of wine to symbolize our sorrow at what befell the Egyptians - the same Egyptians that suposedly oppressed our ancestors for 400 years!! Here is definitely one angle from which to look at Ethics from a Jewish perspective...Power needs to be compassionate. We do not enjoy the suffering of those we overcome, but we integrate their suffering into our own, we empathize with them to remind us that the wheel of history might have us on top one day and at the bottom the next - a lesson that as Jews we learned collectively very well in our History. Point one: Compassion.
The Talmudic discourse is such that it actually encourages a free discussion of ideas, without giving any idea absolute value. All ideas are valuable, be it majority of minority ideas. There is a story about a Rabbi that disagreed with all his colleagues on the issue of how to make an oven Kosher. After hours of bitter argument, this Rabbi gets upset and exclaims: "If I am right, may the tree outside the building uproot itself and start walking", and Lo and Behold, the tree uprooted itself and walked! - yet the rest of the Rabbis exclaimed: we still hold that we are right and you are wrong!; the Rabbi then exclaimed: "If I am right, may the river outside start flowing backwards!" and Lo and Behold, it did! - yet the rest of the Rabbis insisted in their own answers in opposition to the Rabbi...The Rabbi then said: "If I am right, may God him(her)self speak out and may the walls of this synagogue come down on us". And a great Voice comes down from heaven exclaiming: "Why do you keep oppossing my servant who is telling you what is right?" - yet the Rabbis, even scared as they were with the walls falling on them, exclaimed: "The Law is not in Heaven". The story goes that God laughed and conceded the point, so to this day, the walls of that synagogue did not completely fall, because the majority of Rabbis was right, but neither did they go back up because the minority Rabbi was also right!. So point two: Respect all ideas.
Jewish Tradition tells us that the reason that God created only one original couple from which all Humanity came to be is so that nobody will be able to say: "My Father was better than Yours". Point three: All people are equal under the law.
Jewish tradition also tells us that we have an obligation to always considered the consequences that our action - or inaction - might bring to those around us, because actions always have consequences. Point four: act responsibly.
Since my family comes from Radin, in what is today Belarus, I'm particularly fond of the works of Rabbi Israel Meir Kagan, better known as the Chofetz Chayim. He wrote about the consequences of "Lashon HaRah", which can be understood as something in between "gossiping" and "slandering". He suggested that Lashon HaRah damages not only the object of the words, but also the speaker and the listener - and that therefore we should be very careful with what we say. Point five: Be careful with what you say.
In Jewish tradition, when we want to atone for something we did wrong, we are expected to take three steps: First step is to acknowledge our mistake (Humility), second step is to ask forgiveness from everybody affected by our mistake (taking active responsibility) and point three we are expected to change our behavior and not to repeat the same mistake (learning). So points six and seven: Humility and respect of others.
While this far from a tractate on Jewish Ethics of Power (I didn't intend to write one), it does bring out some points of what should be considered Ethical Behavior in those who exercise power. How many politicians would survive if they were required to meet these standards?