U.S. Supreme Court Justice Clarence Thomas occupies a rarified position. He's one of nine individuals who passes what can amount to final judgment on the thorniest issues facing this country. As a body, the Supreme Court has few limits on its judicial authority — or conduct.

That last has grown from a problem to a near-crisis. Reports have shown that Thomas has skirted ethical boundaries, seemingly unable to resist the attentions of wealthy mega-donors such as GOP benefactor Harlan Crow. His 20-year "friendship" — one that conveniently coincides with Thomas' ascension to the high court — has been marked by a stream of luxuries, including lavish cruises to exotic locations: hobnobbing with the powerful at Crow's private resort, flights in Crow's private jet and cozy real estate deals.

Thomas has long been a controversial figure. He started his court appointment under a cloud, dogged by allegations from Anita Hill and others that he had sexually harassed subordinates while at a federal agency. Now he's accused of violating disclosure standards by failing to report gifts from Crow.

This isn't Thomas's first time under scrutiny because of his association with Crow. In 2004, the Los Angeles Times reported that Crow had given Thomas gifts worth tens of thousands of dollars and that Crow's foundation gave more than $100,000 to Thomas' alma mater, Yale Law School, for a "Justice Thomas Portrait Fund."

Now, a recent investigation by ProPublica has revealed that the gifts kept coming for two decades. And the disclosure? Nonexistent.

The extent and frequency of Crow's apparent gifts to Thomas, one vacation alone which totaled in the hundreds of thousands of dollars, the ProPublica report noted, "have no known precedent in the modern history of the U.S. Supreme Court."

Federal employees must adhere to a code of conduct, as must federal judges, who are instructed to avoid even the appearance of impropriety.

But the Supreme Court is different. Because of the separation of powers, there is, admittedly, little that Congress can do to impose a code of conduct — however badly needed — upon the high court, and the justices appear disinclined to impose one on themselves.

Eric Janus, a constitutional law expert and former president and dean of the William Mitchell law school, said that Congress retains the power to impeach, using the same process as for the president. Except that impeachment of Supreme Court justices is even rarer. The only justice to have been impeached was Associate Justice Samuel Chase in 1804. Even then he was acquitted in the Senate.

"The court could clearly set its own rules," Janus said. "Nothing prevents them. But can the other branches impose them? That's the question. If Congress tried, the arbiter of whether it was permissible would be the Supreme Court. The separation of powers is a brilliant way of structurally ensuring that government doesn't become powerful or corrupt. But there are some little areas where there are problems. This is one of them."

Janus said that Chief Justice John Roberts is now in a precarious situation. "He's not really the boss of the other justices, despite the title," Janus said. "And he may not think he has the moral authority to set the direction and standards for the court. On the other hand, moral authority comes from being willing to stand up and say something. If you don't exercise that, you lose it."

Larry Jacobs, director of the Center for the Study of Politics and Governance at the University of Minnesota, told an editorial writer that the real question for the public is why the court appears so resistant to subjecting itself to a code of conduct when the need is so evident.

"There is strong resistance on the court," Jacobs said. "It is jealous of its prerogative and does not want to be policed or have a code used to scrutinize them. That's preposterous. Thomas' conduct is so far beyond the pale that it has triggered widespread outrage and distrust. The court's legitimacy is already clearly being questioned."

The court could, Jacobs said, start with the federal ethics statute that governs federal employees. "That could be extended explicitly to the Supreme Court," he said. "The real question here is do we have a court so determined to be able to act with impunity that it is unwilling to accept pretty commonsense standards.''

Senate Judiciary Chairman Richard Durbin, D-Ill., is calling on Roberts to address the issue and has invited him to testify at a hearing "regarding the need to restore confidence in the Supreme Court's ethical standard."

The Supreme Court needs stronger ethical guardrails. If it remains unwilling to adopt its own, Congress or the Justice Department may be forced to take action. The result could be a constitutional showdown, but the legitimacy of our judicial system is at stake.