From his youthful days as a Reagan administration aide to his current job as a judge on the U.S. Court of Appeals for the District of Columbia Circuit, John G. Roberts Jr. has consistently espoused a clear view of federal judicial intervention: Less is more.

This same principle was held dear by the man Roberts served as a Supreme Court clerk, the late William H. Rehnquist -- whose former position as chief justice of the United States is now suddenly within Roberts's grasp.

In the quarter-century since he served as Rehnquist's aide, Roberts has made an instinctual and deeply held conservatism plain at nearly every turn. As a young Reagan administration aide, he registered his skepticism toward court-recognized "fundamental rights," such as the right to privacy. Earlier this year, Judge Roberts voted to permit President Bush to subject terrorism suspects to military trials at Guantanamo Bay.

The question -- more urgent now since Bush nominated him yesterday morning to lead the high court -- is where Roberts's vision of judicial restraint would lead him on the most volatile issues. The woman Roberts was originally tapped to replace, Justice Sandra Day O'Connor, sometimes displayed her conservatism by bowing to precedents on social issues -- notably Roe v. Wade, which established a right to abortion rooted in a right to privacy. Rehnquist labored mightily to reverse some rulings on abortion and the rights of criminal defendants that he thought were wrongly decided in the first place.

To Roberts's supporters, his history suggests he will be a careful and principled leader of the federal judiciary, one who would restore the true constitutional balance of power between the courts and the people's elected representatives in Congress, the White House and the states.

To his opponents, it suggests a willingness to leave the constitutional rights of women and minorities unprotected against violations by the more political branches of government.

What is unmistakable from Roberts's record, however, is that his essential philosophy about the role of courts in American life is strongly held. There is little prospect that the 50-year-old judge will be any less likely to press his beliefs in conference with colleagues on the court than he was to promote them in memos to his elders in the Reagan administration.

Sounding very much like the 26-year-old aide who ghostwrote articles and speeches on judicial restraint for President Ronald Reagan's Justice Department, Roberts told the Senate firmly in a written submission last month that federal judges "do not have a commission to solve society's problems, as they see them, but simply to decide cases before them according to the rule of law."

The Primacy of Process

Roberts has said that defining the proper boundaries of judicial review is a "central problem" of American government. Few legal analysts of any ideological stripe would dispute that.

Throughout history, the Supreme Court has provoked controversy by using its power to declare laws unconstitutional in ways that critics saw as overstepping its authority.

President Thomas Jefferson condemned the 1803 Marbury v. Madison decision that established the doctrine of judicial review.

The Dred Scott case of 1857 -- which declared that black people were "beings of an inferior order" and that congressional efforts to restrict slavery in northern territories were a violation of property rights -- discredited the institution for a generation. A series of rulings striking down state and federal economic regulations provoked President Franklin D. Roosevelt's "court-packing" plan, until the justices backed down and began upholding New Deal legislation.

In the 1950s and '60s, the Supreme Court looked at the country's problems and decided, time and again, that the federal judiciary should reform society and establish individual rights. Even today, long after the death of the chief justice, Earl Warren, who led the court during that period, and long after a majority of the court has been named by Republican presidents who opposed the Warren Court's innovations, the court continues to recognize such Warren-like concepts as a "fundamental right" to privacy that protects abortion and private consensual homosexual conduct.

The Warren revolution remains a model for many people of how the court must act as a guarantor of individual and minority rights. Roberts, however, was one of those who recoiled from the Warren Court's activism.

Roberts grew up in a mostly white Indiana suburb where his father's steel company was touched by federal court battles over affirmative action, and he attended Harvard College and Harvard Law School as Boston was grappling, sometimes violently, with court-ordered school desegregation.

But his gravitation to concepts of judicial restraint probably reflected the natural bent of his orderly, traditionalist mind, rather than the controversies swirling outside the academic setting in which he spent most of the 1970s.

Asked by a senator in 2003 to name the legal text that most influenced him, Roberts chose the 1973 edition of Hart & Wechsler's "The Federal Courts and the Federal System," a 1,657-page legal textbook used in Harvard's class on federal courts. It has always been "within reach of my desk" since law school, he told the Senate. And, indeed, he has often cited it in his writings since Cambridge.

Unknown to most Americans, the Hart & Wechsler volume is instantly recognizable to law professors as an exhaustive, sophisticated -- and deeply skeptical -- treatment of the Warren Court revolution.

It is considered a virtual Bible of a postwar legal movement known as the Legal Process School, especially influential at Harvard, whose leading figures were liberals and conservatives who professed concern not so much for the results the court was reaching as for the damage its overreaching might do to the judiciary's own legitimacy.

Roberts's choice of the book is "extremely revealing," said Cass Sunstein, a professor of law at the University of Chicago.

For the Legal Process School, it was a given that "judges in solving legal problems are not doing the same thing that legislators are doing in solving political problems," says Todd Rakoff, a professor of law at Harvard.

The strength of Legal Process was its insistence that courts adhere to neutral principles, that they "should not become champions of particular causes or litigants," as Dennis J. Hutchinson, a professor of law at the University of Chicago, puts it.

Yet Legal Process has lost influence in more recent years, under attack from a new generation of law professors who fault it for ignoring the political power relationships embedded in the law -- that its insistence on identifying neutral principles is unrealistic.

"The question about legal process," Rakoff says, "is 'Is it true that there are legal answers that aren't political answers?' "

A Closet Activist?

That, in essence, is the critique liberals are raising about Roberts's jurisprudence today: that his insistence on a limited role for the federal courts is a cover for conservative policy preferences.

Announcing its opposition to Roberts, the Alliance for Justice said that Roberts supports "weakening women's rights and civil rights laws, cutting back the vital role of our courts in enforcing legal protections and restricting the ability of the people's democratically elected representatives to enact crucial, nationwide worker, anti-discrimination and environmental safeguards."

Court conservatives such as Rehnquist and Justices Antonin Scalia and Clarence Thomas have also espoused judicial restraint. Yet that has not prevented them from striking down many federal and state statutes, often on the basis of a states'-rights doctrine that dissenting justices on the court have criticized as too loosely based in constitutional text.

The accusation that Roberts is capable of his own brand of activism has not come exclusively from liberal advocacy groups.

On the D.C. Circuit, he wrote an opinion for a 2 to 1 majority in which he interpreted a law to deny a former Amtrak employee the right to sue the government-subsidized railroad in federal court for allegedly spending taxpayer money on defective railroad cars.

Judge Merrick Garland wrote in dissent that Roberts's opinion "falls back on policy considerations" but "the policy on which the court relies are not those of the Congress of the United States."

But to many, Roberts's intellectual pedigree marks him as a careful "lawyer's lawyer," with a healthy recognition of the courts' -- and his own -- fallibility.

"Of all the people Bush could have nominated, this is a guy who is actually telling the truth when he says he can't decide a case until he's seen the facts and the briefs," says Jonathan Macey, a professor of law at Yale University.

St. John's University law professor John Barrett, noting that Roberts has named legal craftsmen such as Justices Felix Frankfurter and Robert Jackson as the Supreme Court members he most admires, suggests that he "may end up disappointing President Bush."

If he remains true to the legal view embodied by the Legal Process School, Barrett said, "he'll shy from agenda-driven decision making" and respect long-established precedents, even those, such as Roe v. Wade, of which he may disapprove.

"A kind of continuity of judicial decision-making is a value in the process world," Barrett said. "Moderation, deference, continuity, caution, candor -- it's not swing for the fences judging."

Another crucial influence on Roberts's judicial philosophy was Henry J. Friendly, a judge on the U.S. Court of Appeals for the 2nd Circuit in New York, for whom Roberts worked as a law clerk in 1979-1980, just after graduating from Harvard.

Friendly, a Rockefeller Republican who served on the 2nd Circuit from 1959 until his death in 1986, is widely regarded as the most talented appeals court judge of his generation. He was a longtime private-sector lawyer who wrote his own rigorous opinions, as well as many influential law review articles.

He regularly plucked top students from Harvard, where he had studied, to be his aides. Roberts, whose credentials as a prize-winning undergraduate majoring in history and managing editor of the Harvard Law Review matched Friendly's own, got his clerkship without even having to be interviewed, according to Richard J. Lazarus, Roberts's close friend.

Friendly could be a stern taskmaster. "Sometimes the clerk thought he had something interesting to say, and sometimes the judge would disagree," said Macey, also a former Friendly clerk.

Roberts loved him. His esteem is evident not only from his frequent citations of Friendly's work in his own writings, including six of his 49 opinions on the D.C. Circuit, but also from the fact that he corresponded with the judge throughout his time as a Reagan aide.

In one letter, dated Nov. 4, 1981, Roberts told Friendly that it was "an exciting time to be at the Justice Department, when so much that has been taken for granted for so long is being seriously reconsidered." He continued: "You assist us down here every day through the articles and opinions that so often light the way."

Friendly's views on many issues paralleled those of the Legal Process School, says Rakoff, a former Friendly clerk. The 1988 edition of the Hart & Wechsler book is dedicated to him.

Friendly felt that the Warren Court's 1966 Miranda v. Arizona ruling, which created the "right to remain silent," was misguided. In a famous 1970 article, Friendly attacked the Warren Court for opening up state criminal convictions to wide-ranging federal court review.

Friendly felt that a state conviction should usually be challengeable in federal court only when the prisoner also had a strong claim of innocence, rather than wasting the courts' time on technical issues raised by guilty defendants.

But the Warren Court had expanded access to the federal courts as a remedy for what it considered the widespread abuse of rights by state criminal justice systems, especially in the South.

Friendly thought state courts were just as capable of protecting federal constitutional rights as federal courts were.

On Nov. 12, 1981, Roberts offered then-Attorney General William French Smith his unsolicited critique of the Warren Court's decisions, in a memo that cited Friendly's article seven times and the Hart & Wechsler book once.

"The current availability of federal habeas corpus" -- the legal term for post-conviction constitutional challenges -- "particularly for state prisoners, goes far to making a mockery of the entire criminal justice system," he wrote.

In April 2003, Roberts, sitting before the Senate Judiciary Committee as a nominee to the U.S. Court of Appeals for the D.C. Circuit, offered similar comments in response to a question by Sen. Russell Feingold (D-Wis.) about the death penalty -- a major source of habeas corpus petitions in federal court.

Roberts replied that "it's not certain, it's not definite, and there doesn't seem to be any reasonable time limitation. The effectiveness, if you believe in capital punishment, the effectiveness of capital punishment diminishes if the crime was committed 30 years ago. And if it takes that long to get through the system, it's not working, whether you're in favor of the death penalty or against it."

In the meantime, however, conservative critiques of federal habeas had become the law of the land. In 1996, the Republican Congress passed, and President Bill Clinton, a Democrat, signed a bill that sharply restricted access to federal habeas corpus.

Nevertheless, petitions for habeas corpus from state prisoners continue to occupy much of the court's time -- far more than higher-profile issues such as abortion and school prayer.