Following up on this post a reader points me to page 2 of The Guide to Judiciary Policy, which lists the judicial canons. It explains that the canons apply to “United States circuit judges, district judges, Court of International Trade judges, Court of Federal Claims judges, bankruptcy judges, and magistrate judges.” Justices of the Supreme Court are not listed. There still could be an ethical question with a Justice appearing at a fundraiser, particularly for a political group. But it does not appear that Canon 4 is binding on a Justice.