Commentary by Washington Post columnist Alexandra Petri, author of "Alexandra Petri's U.S. History: Important American Documents (I Made Up)": You know how it's a bad sign generally if your neighbors start saying, "Yikes! Maybe it's time we had a policy about not welcoming grizzly bears to the pool!"? It just implies the situation is already out of hand. Well, more and more people are saying, "Yikes! Maybe it's time the Supreme Court adopted some kind of code of ethics!" On the one hand, I love the Supreme Court! I love that they don't have term limits, and it's a comfort...