U.S. Supreme Court Chief Justice John Roberts said on Tuesday that the court is exploring ways to “adhere to the highest standards of conduct,” following congressional examination of a conservative justice’s travel and real estate purchases.

Roberts stated at an American Law Institute event that he is “committed” to ensuring that the court’s nine members achieve such requirements. He did not elaborate on what those actions might entail.

But the chief justice also signaled that he is wary of potential legislation by Congress that could impose an ethics code for the justices.

Roberts said he is “confident there are ways” to make sure the court’s members are meeting their ethical obligations “that are consistent with our status as an independent branch of government under the Constitution’s separation of powers.”

It was the first time Roberts has publicly commented since a U.S. Senate committee hearing earlier this month on a potential ethics code for the high court. The U.S. Supreme Court is the only federal court in the United States that does not have a formal ethics code.

Roberts declined to attend the Senate hearing on Supreme Court ethics issues, but sent to the committee five pages of information about current judicial ethics standards.

While Senate Democrats on the panel have backed potential ethics legislation, Republican members have staunchly opposed it.

The news outlet ProPublica has detailed ties between Justice Clarence Thomas, a conservative who is the court’s longest-tenured member, and wealthy Republican donor Harlan Crow.

Crow’s attorneys this week rejected a bid by Senate Democrats to learn of other gifts given by the Dallas billionaire to Thomas. They argued that Congress lacks the authority to impose an ethics code on the justices.