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Judge John G. Roberts Jr. (search), who has argued 39 cases before the Supreme Court, may get the chance to hear even more cases from the other side of the bench.

In an announcement Tuesday night, President Bush picked Roberts to replace retiring Supreme Court Justice Sandra Day O'Connor (search). He is seen as a solid conservative who has done little to give Democrats much cause for complaint.

But the jurist is unlikely to get off without considerable scrutiny, foremost of which will focus on Roberts' stand on Roe v. Wade (search) — the 1973 case that effectively legalized abortion in the U.S. — a position that he has left largely up in the air publicly.

The landmark decision has had conservatives eagerly awaiting Bush's chance to shake up the high court, which has remained static for nearly 11 years. Meanwhile, Democrats consider the decision to give women access to abortions as perhaps the most vital court ruling to be preserved in a newly configured court.

Roberts, 50, previously served on the U.S. Court of Appeals for the District of Columbia (search); he was confirmed for the position in May 2003. Before that he served President Reagan as associate counsel from 1982-86 and President George H.W. Bush as principal deputy solicitor general from 1989-93. He has argued before the Supreme Court — both in private practice and on behalf of the United States — on cases ranging from environmental law to the First Amendment and antitrust cases.

Unlike Justice Antonin Scalia, who was also nominated off the D.C. Appeals Court, Roberts spent no time in academia following his graduation from Harvard Law School in 1979. The lack of a substantial paper record of Roberts' judicial philosophy will no doubt frustrate those seeking predictive clues to what kind of justice he will be.

Sen. Charles Schumer, D-N.Y., said the onus is on Roberts, not the Senate, to prove his mettle.

"It is vital that Judge Roberts answer a wide range of questions openly, honestly and fully in the coming months," Schumer told reporters following Bush's announcement Tuesday night. "His views will affect a generation of Americans and it is his obligation during the nomination process to let the American people know those views."

Schumer was one of three Democrats who voted against Roberts' appointment to the Appeals Court because, he said, the then-lawyer refused to reveal which Supreme Court decisions he opposed, including the monumental abortion case.

In a brief filed in 1991on behalf of the first Bush administration, Roberts wrote: "We continue to believe that Roe was wrongly decided and should be overruled."

But during his confirmation hearings in 2003, Roberts insisted that the brief contained the administration's opinion, not necessarily his own.

"The statement in the brief was my position as an advocate for a client," he said.

Roberts also insisted he would respect Supreme Court precedent.

"Roe v. Wade is the settled law of the land. ... it's a little more than settled. It was reaffirmed in the face of a challenge ... There's nothing in my personal views that would prevent me from fully and faithfully applying that precedent," Roberts said in response to a question from Sen. Richard Durbin, D-Ill.

That so little is known about Roberts means that it may well be after his first day on the bench before any camp can declare his confirmation a victory. Special interest groups had already begun expressing their opinions by time the president's announcement was finished.

"The nomination of John G. Roberts raises serious questions and grave concerns for women's health and safety. It is particularly troubling that Roberts went on the record calling for Roe v. Wade to be overturned when he served as a lawyer for the government," said Karen Pearl, interim president of Planned Parenthood Federation of America. "Only a nominee committed to protecting women's health and safety should be confirmed by the Senate."

"Everything we know about Judge Roberts tells us that he fulfills the president's promise to nominate a judge who will strictly interpret the Constitution and not legislate from the bench," said Jan LaRue, chief counsel of the conservative group Concerned Women for America. "That's why the president nominated him to the D.C. Circuit. He clerked for (Justice William H.) Rehnquist, which says a lot."

Meanwhile, Republican presidents in the past couple decades have been hurt by unknowns appointed to the bench. Justices David Souter and Anthony Kennedy have proved to be more liberal-leaning than expected, much to the disappointment of anti-abortion conservatives.

Roberts was born Jan. 27, 1955, in Buffalo, N.Y. Raised in Indiana, Roberts worked summers in a steel mill to help pay his way through Harvard, where he graduated summa cum laude in 1976. After graduating from the law school magna cum laude, Roberts clerked for Judge Henry Friendly on the 2nd Court of Appeals.

In 1980, he served as a clerk for then-Associate Justice Rehnquist. Twenty-three years later, the chief justice swore his former clerk into the D.C. Appeals Court. The confirmation to that court was among the least contentious of the Senate since Bush's tenure began.

Roberts, a practicing Catholic, lives with his lawyer wife and their two children in Bethesda, Md.