The nine members of the Supreme Court. Front row, from left: Clarence Thomas, Antonin Scalia, John Roberts, Anthony Kennedy, Ruth Ginsburg. Back row, from left: Sonia Sotomayor, Stephen Breyer, Samuel Alito, Elena Kagan. (Bill O'Leary/WASHINGTON POST)

Chief Justice John G. Roberts Jr. defended his colleagues as “jurists of exceptional integrity and experience” and said Saturday that it was a misconception that Supreme Court justices do not follow the same set of ethical principles as other judges.

In his year-end report on the state of the federal judiciary, Roberts for the first time addressed a growing controversy about when justices should recuse themselves from cases and whether a code of conduct that covers lower-court judges should apply to the justices as well.

Roberts, in polite but firm language, made it clear that such decisions must rest with the judiciary and did not suggest any changes.

The recusal issue has been most prominent as the court prepares to address the constitutionality of the health-care overhaul law.

Groups on the right have demanded that Justice Elena Kagan withdraw from the court’s consideration of the case because of her work for President Obama as solicitor general. Liberal groups have called on Justice Clarence Thomas to recuse himself because of the conservative political activities of his wife, Virginia Thomas.

Roberts said he could not comment on “ongoing debates about particular issues,” but noted that one of the original canons of judicial ethics adopted in 1924 said judges “should not be swayed by partisan demands, public clamor or considerations of personal popularity or notoriety, nor be apprehensive of unjust criticism.”

“I have complete confidence in the capability of my colleagues to determine when recusal is warranted,” Roberts wrote. “They are jurists of exceptional integrity and experience whose character and fitness have been examined through a rigorous appointment and confirmation process.”

He added: “We are all deeply committed to the common interest in preserving the court’s vital role as an impartial tribunal governed by the rule of law.”

Federal law requires judges and justices, including those on the Supreme Court, to disqualify themselves when their “impartiality might reasonably be questioned,” as well as for specific reasons such as a financial interest or the involvement of a family member in the litigation.

In addition, it calls for recusal when the judge has served in the government and “participated as counsel, adviser or material witness concerning the proceeding or expressed an opinion concerning the merits of the particular case in controversy.”

Roberts said the public should keep in mind a key difference between lower-court judges and Supreme Court justices: While lower-court judges can be replaced when they recuse themselves from cases, that is not the case at the “court of last resort.”

“A justice accordingly cannot withdraw from a case as a matter of convenience or simply to avoid controversy,” Roberts wrote. “Rather, each justice has an obligation to the court to be sure of the need to recuse before deciding to withdraw from a case.”

Allowing the court itself to decide whether justices should recuse, Roberts said, “would create an undesirable situation in which the court could affect the outcome of a case by selecting who among its members may participate.”

Roberts also addressed the view of some law professors and members of Congress that the Judicial Conference’s Code of Conduct for lower-court judges should also apply to Supreme Court justices.

Roberts said charges that “the Supreme Court is exempt from the ethical principles that lower courts observe” is based on “misconceptions about both the Supreme Court and the code.”

Justices consult the code as a “starting point,” but it cannot answer all questions, he said. Justices may also “turn to judicial opinions, treatises, scholarly articles and disciplinary decisions” as well as seeking advice from experts and from their colleagues.

Some Democratic House members have proposed legislation that would require the justices to follow the code. While Roberts did not address whether such a requirement would violate the separation of powers between the legislative and judicial branches, he noted twice that the judiciary complied with some legislative dictates — such as financial disclosure — even though the court had never agreed Congress had such powers.

Steven Lubet, a judicial ethics expert at Northwestern University School of Law, thought Roberts was sending a clear message. “I think he’s laying down the law," Lubet said.

Lubet and another scholar who studies the court, Russell Wheeler of the Brookings Institution, said they did not expect Roberts’s explanations to satisfy those who have recently criticized the court. But both praised the effort.

“There’s value in him laying out what the justices do,” Wheeler said.

Added Lubet: “It’s very good that he’s chosen to address the issue. There’s not been the opportunity for much exchange between the public and the court.”