Judges in the United States are subject to a formal code of ethics.

More accurately, all but nine of them are.

Recent revelations of ethical misconduct by Justice Clarence Thomas, and the manner in which the U.S. Supreme Court has thus far chosen to respond to them, offer the latest proof that this exception urgently needs to change.

A bipartisan bill mandating a code of ethics for the nation’s highest court, co-sponsored by Maine Sen. Angus King, could be just the ticket.

The most recent episode of national legal ethical soul-searching was prompted by an April report by the nonprofit newsroom ProPublica into Justice Clarence Thomas’ yearslong receipt of cash and gifts in a dazzling array of forms from a Texan billionaire and Republican Party donor named Harlan Crow.

Crow’s generosity to Thomas has ranged from presents of a bust of Abraham Lincoln and a Bible once owned by Frederick Douglass, to travel on private jets and megayachts worth hundreds of thousands of dollars, to a series of eyebrow-raising real estate transactions (Crow bought Thomas’ mother’s home in Savannah, Georgia, for example, to “preserve it for posterity”).

The Thomas-Crow scandal deepened again last week as the same newsroom revealed that Crow also paid up to $150,000 in private school tuition for a grandnephew Thomas said he was “raising as a son.” In the absence of an effective formal code of conduct, how much of it should or shouldn’t have been reported by Thomas is being debated. What matters, though, is it wasn’t reported. The public would know nothing about most of this epic looseness were it not for the work of investigative journalists.

Infused with what a columnist writing for the Hill earlier this week described as an “historic aversion to questioning about their internal operations,” Chief Justice John Roberts’ response to the controversy on behalf of the court was to release a signed “Statement of Ethics Principles and Practices.”

Case closed? Not nearly.

The argument against new rules by Roberts has been that the rules applying to other judges shouldn’t apply to Supreme Court justices because they are not the same. And they’re not the same: Roberts and his counterparts have far more power and influence.

The “three I’s” so often used in legal and judicial teaching – impartiality, independence and integrity – are of far weightier importance at the top. Although Thomas is at the center of the latest uproar, question marks over the conduct of other justices over the years suggest that the court’s commitment to self-policing hasn’t been rigorous enough at all.

Tight oversight – the style outlined in other proposals for reform – is not the answer; it would be unconstitutional for Congress to take the reins here.

The Sen. King bill, introduced with Rep. Lisa Murkowski, a Republican from Alaska, respects the separation of powers by directing the court to come up with its own code – the text of the proposal gives it a year in which to do it – publish it, and appoint a person to review complaints as they arise and publish an annual report detailing those complaints and any remedies taken.

Every state has a judicial conduct commission or committee, a body that can receive complaints about judges and investigate those complaints. The question of gifts is prominent in the state codes, including Maine’s, which is so detailed as to make an express exception for “plaques, pens, mugs, certificates, trophies and greeting cards.”

Gesturing at these many working codes in a recent radio interview, Sen. King said of creation of a formal code by the Supreme Court: “A, it’s easy to say what it would look like, and B, it shouldn’t be a great chore to draft it.”

Much of the resistance to reform has characterized it as cynical political maneuvering. At a Senate Judiciary Hearing hearing last Tuesday, Sen. Lindsey Graham criticized “an unseemly effort by the Democratic left to destroy the legitimacy of the Roberts court.” Sen. Ted Cruz called out “despicable tactics.”

In a statement responding to the subject of the $6,000-per-month tuition payments to Thomas for his relative, Harlan Crow’s office struck the same note. “It’s disappointing that those with partisan political interests would try to turn helping at-risk youth with tuition assistance into something nefarious or political,” the statement read.

Such a sanctimonious defense would be amusing were it not so wildly off the mark.

You don’t need to be an expert in legal ethics to understand that an independent and honorable judiciary is the concern of people of every political persuasion, or it should be. The Supreme Court has already lost a lot of ground with the American public. We feel it has no more to lose.

The King-Murkowski bill represents a simple and appropriate intervention, if an optimistic one. It is our hope that a proposal so plainly rooted in improving basic transparency – at a time it is sorely needed – might enjoy the congressional support it deserves.