During a question-and-answer session Wednesday after an address at the University of Arizona's law school, Roberts was asked whether growing partisanship in the confirmation process poses a significant threat to the independence of the judiciary.

"The courts as a whole are very concerned about partisanship, politicization, seeping into the judicial branch," he said.

Roberts said he thought he was treated fairly during his confirmation hearings, receiving "significant support from both sides of the aisle. But that's not always the case, and what do we do about it?

"I think we need to have a broader recognition that we are not part of the political process, that we are not representatives of either an administration or a confirming Senate on the court," Roberts added. "Your perspective on everything changes the moment you take the judicial oath."

Roberts' lecture focused on his predecessor, the late Chief Justice William Rehnquist.

Roberts called Rehnquist one of the two or three most significant Supreme Court chief justices in history — responsible for a "seismic shift" away from political science and public policy "to the more solid grounds of legal arguments" in case presentations before the court.

"Today, for the first time in its history, every member of the court was a federal court of appeals judge before joining the court — a more legal perspective and less of a policy perspective," Roberts said.

Roberts was named to the high court in September 2005 to succeed Rehnquist. He gave the college's third annual Rehnquist Center Lecture.

Roberts said that during Rehnquist's 33-year tenure on the Supreme Court, he argued 39 cases before him. "Each of those arguments was a lesson, sometimes a hard one in lawyering," he said.