Updated

Chief Justice John Roberts walked out of a hospital in Maine Tuesday, released a day after he suffered a seizure. The White House said he told President Bush he was doing fine.

Roberts strode briskly out of the Penobscot Bay Medical Center in Rockport, Maine, wearing a blue sport coat, open collar shirt and slacks. He waved to onlookers before getting into a waiting sports utility vehicle.

The chief justice, 52, plans to continue his summer vacation, Supreme Court spokeswoman Kathy Arberg said. She said that doctors found no cause for concern after evaluating Roberts.

Roberts was hospitalized after he fell on a dock near his summer home on Hupper Island, near Port Clyde, Maine. He had a prior unexplained seizure in 1993. Bush had called Roberts earlier Tuesday, and press secretary Tony Snow said that the president was assured the chief justice was doing well.

Snow said that Roberts "sounded like he was in great spirits."

Doctors who examined Roberts after his seizure said they found no tumor, stroke or any other explanation for the episode.

Roberts told the White House of his previous seizure when Bush nominated him to the nation's highest court and "it was taken into consideration," Snow said. Roberts also had physical exams which were forwarded to relevant members of Congress. "He was very open about it," Snow said.

The spokesman did not know whether outside experts were consulted or whether Bush himself was informed at the time, but said it was determined that Roberts had a clean bill of health and was competent to serve.

Two Senate Judiciary Committee aides who were involved in Roberts' confirmation hearing in 2005 said the committee was aware of a previous seizure whose cause was never diagnosed. The sources would not say whether Roberts disclosed that he took any medication as a result. Such health information is often provided to the panel in private briefings, according to the sources, who spoke on condition of anonymity because of the sensitivity of the issue.

By definition, someone who has had more than one seizure without any other cause is determined to have epilepsy, said Dr. Marc Schlosberg, a Washington Hospital Center neurologist who is not involved in the Roberts case.

Whether Roberts will need anti-seizure medications to prevent another is something he and his doctor will have to decide. But after two seizures, the likelihood of another at some point is greater than 60 percent.

Epilepsy is merely a term for a seizure disorder, but it is a loaded term because it makes people think of lots of seizures, cautioned Dr. Edward Mkrdichian, a neurosurgeon at the Chicago Institute of Neurosurgery and Neuroresearch.

Still, Mkrdichian said anyone who has had two otherwise unexplained seizures is at high risk for a third, and that he puts such patients on anti-seizure medications.

"Having two seizures so many years apart without any known culprit is going to be very difficult to figure out," agreed Dr. Max Lee of the Milwaukee Neurological Institute.

The incident occurred around 2 p.m. on a dock near Roberts' summer home in Port Clyde on Maine's Hupper Island. He had just gotten off a boat and was returning home after running errands, Arberg said. Port Clyde, which is part of the town of St. George, is about 90 miles by car northeast of Portland, midway up the coast of Maine.

Roberts was taken by private boat to the mainland and then transferred to an ambulance, St. George Fire Chief Tim Polky said.

"He was conscious and alert when they put him in the rescue (vehicle)," Polky said.

Once at the hospital, he underwent a "thorough neurological evaluation, which revealed no cause for concern," Arberg said.

Named to the court by Bush in 2005, Roberts is the youngest justice on a court in which the senior member, John Paul Stevens, is 87.

Roberts is the father of two young children.

Larry Robbins, a Washington attorney who worked with Roberts at the Justice Department in 1993, said he drove Roberts to work for several months after Roberts' seizure that year. Robbins said Roberts never mentioned what the problem was and he never heard of it happening again.

In 2001, Roberts described his health as "excellent," according to Senate Judiciary Committee records.

Roberts became chief justice after the death of William Rehnquist in September 2005, although Bush had first chosen him to take Sandra Day O'Connor's seat when she announced her retirement earlier that year.

Roberts has led the Supreme Court to a more conservative stance. Helped by Justice Samuel Alito, who won confirmation in early 2006, conservatives have won twice as often as they lost on the Roberts-led court. The 2006-07 term brought limits on abortion rights, restrictions on school integration programs and greater freedom for political advertising.

Roberts earlier served as an appellate judge in Washington and spent more than a decade before that as a lawyer at the Hogan and Hartson law firm, where he specialized in arguing cases before the Supreme Court.

Roberts also served in the Reagan and Bush administrations in the 1980s and 1990s. He was a clerk for Rehnquist after graduating from Harvard Law School.

Roberts spent a couple of weeks in Europe in July, teaching a course in Vienna and attending a conference in Paris. He was at the court in Washington late last week.