Four of the five Democratic senators already running for president have signed on to a bill requiring the Supreme Court to adopt a code of ethics.
The nine justices are not bound by the code of conduct that governs all other federal judges.
Members of the high court have successfully resisted legislation, pushed in every Congress since the early 1970s, mandating a Supreme Court code of conduct. The justices argue such legislation would be an improper meddling in the separation of powers, pointing out that the Constitution allows the justices to serve so long as they exhibit "good behavior" or face possible impeachment by the House and removal by the Senate for "treason, bribery, or other high crimes and misdemeanors."
A dozen Democrats (but no Republicans) have signed on to this year's version of the ethics bill, including 2020 presidential aspirants Kamala Harris of California, Cory Booker of New Jersey, Amy Klobuchar of Minnesota and Kirsten Gillibrand of New York. Bernie Sanders of Vermont, who has not yet said definitively if he will run again, is also a co-sponsor. Elizabeth Warren of Massachusetts, who formally launched her candidacy over the weekend, is not.