WASHINGTON – Supreme Court nominee John Roberts received a “well qualified” rating from the American Bar Association yesterday, clearing another hurdle in his path to the nation’s highest court.

The rating – by unanimous vote of an ABA committee – was revealed as the Senate Judiciary Committee announced its plans for Judge Roberts’s September 6 confirmation hearings. The schedule includes having the nominee questioned by the 18 senators on the panel for almost an hour each.

The committee also will hold one hearing that will be closed to the public, leaders said.

This is the fourth time the ABA has rated Judge Roberts. He was designated as well qualified in 2001 when nominated to be an appeals court judge in the District of Columbia and again in 2003 when he was re-nominated and confirmed. He had been rated qualified as an appeals court nominee in 1992, but the Senate never took up that nomination.

Judge Roberts, 50, will replace retiring Justice O’Connor if he is confirmed by the Senate.

For more than 50 years, the ABA has evaluated the credentials of people chosen for federal judgeships. Supreme Court nominees get the most intensive scrutiny.

A 15-member ABA committee handled the work, including a review of opinions and legal briefs, and voted that Judge Roberts was well qualified to be a justice. ABA spokeswoman Nancy Slonim said the vote was unanimous.

The possible ratings are “well qualified,” “qualified,” and “not qualified.”

The Senate Judiciary chairman, Arlen Specter, and a top Democrat, Patrick Leahy, said yesterday that Judge Roberts would have to face almost an hour’s worth of questions from each committee member before his confirmation process ends.

Each senator will get at least 50 minutes to question Judge Roberts and listen to his answers: 30 minutes in a first round and 20 minutes in a second round, the two senators said. Specter and Leahy also said in a letter to Judiciary members that more rounds for questioning could be scheduled if necessary.

Judge Roberts will be able to give an opening statement on the first day of the hearings, after the 18 senators give 10-minute opening statements and Judge Roberts is sworn. The questioning is to begin on September 7.

Messrs. Specter and Leahy also revealed in the letter that the committee will be having a hearing on Judge Roberts that will be closed to the public. Mr. Specter said earlier this year that he might hold closed hearings if there is confidential information to discuss.

More than 1,700 Roberts documents are also being kept private from the Senate and the public by the National Archives and the Ronald Reagan Presidential Library, officials said yesterday.

The material is part of nearly 50,000 pages of records related to Judge Roberts’s time as associate counsel to President Reagan.

The National Archives in Washington and the Reagan Library in Simi Valley, Calif., will release more than 38,000 documents involving Judge Roberts today.