The central question on Alito: Is he activist?

WASHINGTON -- Samuel A. Alito Jr.'s chances of being confirmed as a Supreme Court justice could turn on whether the public comes away from next week's confirmation hearings believing he is a conservative judicial activist or merely a conservative judge.

A conservative judge is a careful reader of legal precedents who is inherently cautious about advancing new interpretations. A conservative judicial activist seeks to change the court's past interpretations to suit his agenda.

If there's one point of agreement to emerge from the two months of political vetting since Alito's nomination, it's that most of his supporters and most of his detractors believe that conservative judges are worthy of confirmation, but conservative activists (or any activists) are not.

But there is no bright line between conservative judges and activists. Even cautious Supreme Court justices don't hesitate to overturn cases that they believe have been wrongly decided; and even highly committed activists defer to precedent in some areas.

Alito's predilections won't be discerned from any single case or long-ago memo. But, unlike Supreme Court Chief Justice John G. Roberts Jr., who had only two years of judicial opinions when he came up for confirmation in September, Alito has a 15-year track record as an appeals-court judge, plus a long tenure in the Justice Department during the 1980s.

The lengthy paper trail will constrain Alito in answering questions from the Senate Judiciary Committee. Unlike Roberts, who dazzled senators with textbook responses, Alito won't be able to pacify critics by giving a professorial overview of the law: Each of his responses will be measured against his long record.

If the senators do their homework, the public should emerge with a clearer picture of Alito's views. And the record itself, which has been coming to the public's attention in dribs and drabs through journalistic examination of cases and the release of documents by the National Archives, should provide fodder for a week's worth of questions.

There are, for instance, many times when Alito applied strict conservative readings of the Constitution in highly charged cases that other judges viewed differently.

He voted to strike down a ban on the sale of machine guns because he felt Congress lacked the power to regulate such sales. He voted to allow a public high school to include a prayer in its graduation ceremony, on the grounds that students preferred it to a moment of silence. He said a police officer couldn't be sued for strip-searching a 10-year-old girl if he reasonably believed he had a warrant to do so, even if he didn't have one.

And, in a case that later went to the Supreme Court, he declared that requiring married women to inform their husbands of their plans to have an abortion did not pose an ''undue burden" on a woman's rights.

To critics, these decisions are the work of an activist who seeks to limit congressional power, allow a greater role for religion in public life, reduce constraints on law-enforcement officers, and make it harder for women to get abortions.

To his supporters, the decisions show a conservative judge's fidelity to the Constitution, assuring that activities within individual states can't be regulated by Congress, as in the machine-gun case, but otherwise giving deference to legislatures and law-enforcement officials.

Alito's critics buttress their case by pointing to memos from his Justice Department career that, they say, go beyond analyzing cases to express enthusiasm for the conservative agenda.

''No one seriously believes that the Court is about to overrule Roe v. Wade," he wrote in 1985. ''But the Court's decision to review these cases nevertheless may be a positive sign."

Alito's supporters say this memo -- and others suggesting strategies to advance conservative causes -- must be viewed in the context of a lawyer helping his client, the conservative Reagan administration.

Most of the disputes about Alito turn on his motives -- essentially, whether he seeks to impose a political agenda on the courts.

Alito's motives ought to be discernible by a panel of tough questioners fortified with a quarter-century of legal writings. Much will depend on how seriously the senators take their roles as questioners.

Initial signs are good. Many Democrats have expressed deep concerns about Alito, but most have also promised to keep an open mind. The Judiciary Committee's Republican chairman, Arlen Specter, has been supportive of Alito but also vowed to be a tough inquisitor.

If the senators fulfill their responsibilities, next week's hearings will be the most revealing in decades.

Peter S. Canellos is the Globe's Washington bureau chief. National Perspective is his weekly analysis of events in the capital and beyond.