Early in yesterday's hearing into his nomination to be chief justice, John G. Roberts Jr. took the Senate Judiciary Committee in an unexpected direction, praising Justice Robert H. Jackson, who served as Franklin D. Roosevelt's attorney general before joining the high court.

"As he went on the court," Roberts told the senators, "he took an entirely different view of a lot of issues, in one famous case even disagreeing with one of his own prior opinions. He wrote a long opinion about how he can't believe he once held those views."

The committee's ranking Democrat, Sen. Patrick J. Leahy (Vt.), was puzzled. "Are you sending us a message?" the senator asked. Laughter bubbled from the gallery.

Roberts added that Jackson "recognized, when he became a member of the Supreme Court, that his job had changed And he took a different perspective. And that's, again, one reason many admire him, including myself." A couple of the conservatives on the committee looked up anxiously.

The exchange was emblematic of Roberts's performance on the first day fielding questions. Roberts, star litigator, adviser to presidents and top-flight jurist, showed that he could be something else: the very model of an enigmatic nominee. The Roberts who answered questions for eight hours yesterday was very much the Roberts who emerged in his writings released over the summer. He maddened the committee's Democrats, delighted its Republicans and charmed most of both.

He was sharp-tongued. When Leahy made a skeptical query about one of Roberts's Reagan administration memos, the nominee retorted: "Senator, you're vastly over-reading the memorandum."

He was quick on his feet. When Sen. Joseph R. Biden Jr. (D-Del.) fired off a series of questions without allowing Roberts to answer, the nominee finally replied: "Well, I was about to lay it out. You said you didn't want to hear about it." The room filled with laughter. Biden did not smile.

And he showed flashes of wit. Asked about an old memo he wrote supporting judicial term limits, he admitted: "You know, that would be one of those memos that I no longer agree with, senator. I didn't fully appreciate what was involved in the confirmation process when I wrote that."

Asked about the views of Justice David H. Souter, Roberts replied: "Well, I don't want to directly comment on what Justice Souter said. He is either going to be a colleague or continue to be one of my bosses."

In constitutional matters, the nominee proved deft at saying much and giving away little. The only time Roberts seemed flustered was when Sen. Lindsey O. Graham (R-S.C.) dropped the legalese. "I think it stinks that somebody can burn the flag, and that's called speech. What do you think about that?"

"Well," Roberts began, then paused, searching for words.

What Roberts did best -- or, at least, most -- was deflect questions on charged issues.

Roe v. Wade ? "I think I should stay away from discussions of particular issues that are likely to come before the court again."

War powers? "I don't want to answer a particular hypothetical."

Voting rights? "Those cases come up all the time, and I do need to avoid expressing an opinion."

Sitting at a folding table dressed up with red felt, Roberts, his bald spot exposed under the studio lights, offered a stream of such evasions: "I don't think I should express a determinative view. . . . I should not respond. . . . I can't answer that. . . . I do not feel it appropriate for me to comment."

The most inflammatory subject -- abortion -- was essentially off-limits. Both sides claim they have no "litmus test" and therefore cannot ask Roberts his views on abortion. "It's the 600-pound elephant in the room," Sen. Sam Brownback (R-Kan.) told reporters during a break. Instead, they got at the subject elliptically, asking Roberts about his view of stare decisis , the Latin term for letting precedent -- in this case, Roe v. Wade -- stand. The word abortion was uttered only six times in the first four hours of the hearing; stare decisis was cited 34 times.

Sen. Arlen Specter (R-Pa.), chairman of the Senate Judiciary Committee, started things off with a query about "the issue of stare decisis and the issue of precedents."

Roberts knew where this was going. "While I'm happy to talk about stare decisis and the importance of precedent, I don't think I should get into the application of those principles in a particular area," he said.

Specter, shifting from the Latin, wondered whether " Roe might be a super-duper precedent."

Roberts finally showed some leg on stare decisis . Roe "is settled as a precedent of the court," he said, "entitled to respect under principles of stare decisis ."

That was about the most the senators could get out of Roberts.

Roberts told Biden that the 14th Amendment protected a right to privacy -- an apparent nod to abortion rights -- but immediately qualified that by saying: "I think every justice on the court believes that, to some extent or another."

He seemed to take pleasure in the ambiguity. Recalling his clerkship for Judge J. Henry Friendly, he mentioned, approvingly: "He liked the fact that the editorialists of the day couldn't decide whether he was a liberal or a conservative."

Even Sen. Edward M. Kennedy (D-Mass.), conqueror of Robert H. Bork, drew little blood. Roberts brushed off Kennedy's complaints about his 1980s memos questioning voting rights laws. "This was 23 years ago," the judge replied. "It was the position of the Reagan administration."

When Kennedy accused him of opposing a civil rights act, Roberts gave no ground. "No, Senator," he said. "You have not accurately represented my position."

The confrontation over, Roberts stood up and exhaled deeply. Kennedy gritted his teeth.