The more-provocative labels hurled at John Roberts by the dozens of liberal groups opposing his nomination seem unlikely to stick, especially once the nation gets to know him through his televised confirmation testimony after Labor Day.

"Extreme"? This may be the most likable, even-tempered, moderate-spirited nominee in recent memory. True, the more than 60,000 pages of now-public Roberts documents show him to be (or, at least, to have been) a committed legal and political conservative and a trenchant critic of many Supreme Court precedents beloved by liberals. But he has consistently rested his arguments on powerful legal analyses and on the highly defensible premise that the Court should not "view itself as ultimately responsible for governing all aspects of our society," as he put it in a 1983 memo.

"Ideologue"? Roberts has won the personal esteem of many liberals as well as conservatives. He hardly appears to be a man on a Bork-style mission to topple decades of precedent or revolutionize the law. While usually on the conservative side, he has also argued forcefully for a pro-environment client, for native Hawaiians seeking racial preferences, and for poor plaintiffs in a welfare-rights case. (Not to mention his minor but telling assistance in a big gay-rights case.)

"Out of step with ordinary Americans"? Most (or at least many) of the views championed by Roberts as a fast-rising young lawyer in the Reagan and first Bush administrations are more in step with those of ordinary Americans than are the views of his critics.

Still, there is a large kernel of truth in the hundreds of pages of reports by liberal groups about what Roberts had to say during his years as a special assistant in the Justice Department (1981-82), an assistant White House counsel (1982-86), and deputy solicitor general (1989-92).

Unless he has changed his mind about a lot of things — which seems unlikely, although he has shed some youthful cocksureness over the years — Roberts may well tip the Court’s precarious balance perceptibly to the right on some big issues. Especially those on which the swing-voting Sandra Day O’Connor has sided with the Court’s four liberals.

For better or worse, that could change the law — perhaps dramatically, if one of the liberals, such as 85-year-old John Paul Stevens, steps down. Whether such a change would be to your liking depends on whether you would prefer that the Court remain to the left of public opinion on most big issues, which is where it has been for at least the past 50 years and where most law professors and journalists would like it to stay.

The Roberts documents show him to have been a Reagan Republican with a deeply felt conviction that judges should stop (or be prevented from) invading the province of elected officials in the guise of constitutional interpretation. He touched on the same theme this summer in his response to a Senate Judiciary Committee questionnaire, asserting that judges "do not have a commission to solve society’s problems" and should practice "institutional and personal modesty and humility."

Roberts also bowed to the need to respect precedent, which, he said, "plays an important role in promoting the stability of the legal system." But the principle of modesty in the exercise of judicial power will clash with respect for precedent in every case in which the relevant precedent strikes Roberts as an immodest intrusion into the legislative or judicial realm. There may be many such cases. Even Roberts himself probably does not know how he will resolve them. But here are some predictions as to how he might differ from O’Connor:

Abortion. Roberts may be in a position to move the Court by next June toward upholding greater legislative restrictions on abortion than O’Connor has allowed, although no case involving a broad attack on the basic abortion right created by Roe v. Wade is on the horizon.

On November 30, the justices will hear a challenge to a New Hampshire law requiring parental notification (or judicial approval) before minors can be given abortions. They will also be asked in the coming months to review a so-far-successful challenge to the 2003 congressional ban on "partial-birth" abortion. Lower courts have held both laws unconstitutional on their face because (among other things) they lack explicit exceptions for abortions deemed by doctors to be necessary to protect the woman’s physical or emotional health.

O’Connor would probably have been the fifth vote to strike down both laws, based on her vote in 2000 to void a Nebraska "partial-birth" abortion law with no health exception. Roberts might well become the fifth vote to uphold both laws, and possibly even to overturn the 2000 decision.

Roberts famously helped prepare a 1990 Supreme Court brief restating (in a footnote) the first Bush administration’s view that "Roe was wrongly decided and should be overruled." He has cautioned against assuming that this was or is his personal view. Fair enough — especially as to the "should be overruled" part, and especially after 15 years during which six of the current justices (including O’Connor) have repeatedly reaffirmed Roe. Indeed, in seeking his current job as a judge of the U.S. Court of Appeals for the District of Columbia Circuit two years ago, Roberts testified that Roe was "the settled law of the land."

But it’s hard to imagine Roberts differing from the consensus of conservative legal experts — as well as many moderates and even some liberals — that Roe had little or no basis in the Constitution and should at least be construed narrowly, if not overturned.

Racial preferences. In 2003, in a 5-4 decision upholding the racial preferences in admissions at the University of Michigan Law School, O’Connor moved the Court toward greater acceptance of affirmative-action preferences than ever before, at least in education and perhaps also in employment and contracting.

Roberts may move the Court in the opposite direction. The memos and briefs he wrote while in government exude dislike of "quotas" and other racial preferences, and of using the Voting Rights Act to require race-based election districts.

On the other hand, it would be surprising to see Roberts translate his policy objections into a broad-based constitutional ban on racial preferences. That would be a most immodest exercise of judicial power, junking not only the 2003 precedent but also the considered judgments of Congress, the military, most states, and almost all universities that preferences are sometimes necessary to promote diversity.

Sex discrimination. O’Connor has usually sided with plaintiffs and feminist groups in sex-discrimination lawsuits and has tilted the Court toward a broad view of Title IX. That’s the 1972 federal law that courts have used to require colleges receiving federal money to equalize female and male athletic opportunities — even when that means ending dozens of wrestling programs around the country.

Roberts has been more skeptical of the use of lawsuits and federal regulations to promote equal opportunity, as his opponents have stressed. This could make a difference in more than a few cases. In 1999, for example, O’Connor wrote a 5-4 decision allowing lawsuits against federally funded schools and universities for "deliberate indifference" to the need to protect against student-on-student sexual harassment. Roberts might well have sided with the dissenters, who warned of a "flood of liability" potentially "crushing" school districts and soaking local taxpayers.

Religion. O’Connor was the fifth vote in both the June 27 decision ordering removal of certain Ten Commandments displays from courthouses and a 1992 decision holding unconstitutional a brief, nondenominational prayer at a public school graduation. Roberts might have tipped the balance the other way in both cases. In 1985, he faulted the Court for "hostility to religion" and assailed as "indefensible" a decision striking down an Alabama moment-of-silence law. And as deputy solicitor general, he defended the graduation prayer as noncoercive and constitutionally innocuous.

Presidential power. President Bush has claimed virtually unlimited powers to detain and interrogate suspected "enemy combatants" indefinitely with no semblance of due process, and to try them in Bush-created military tribunals that critics call kangaroo courts. His detention policies brought Bush two sharp rebuffs from the Court in June 2004, with O’Connor in the majority. Roberts, on the other hand, took a broad view of executive power in a July 15 decision upholding the legality of Bush’s military tribunals. The opinion, which Roberts joined but did not write, was rather cavalier in dismissing the most cogent points raised by the defense lawyers.

Does this opinion foreshadow a blank-check approach that could facilitate creeping presidential autocracy? That is probably the most important of all the questions for senators to explore when Roberts testifies.