How he may rule in abortion cases is particularly relevant to the inquiry since President Bush has named him to replace retiring Justice Sandra Day O'Connor, a key swing voter and defender of abortion rights.
If Alito holds a different view on that issue, his vote could shift the balance of power on the court. His four abortion cases include:
• A 1991 challenge to a Pennsylvania law requiring married women to notify their husbands before seeking an abortion. The court struck down the restriction. Alito dissented.
• A 1995 challenge to a Pennsylvania law that required women seeking to use Medicaid funds to abort a pregnancy resulting from rape or incest to report the incident to law enforcement officials and identify the offender. Alito provided the decisive vote striking down the abortion restriction.
• A 1997 challenge to a New Jersey law that prevents parents from suing for damages on behalf of the wrongful death of a fetus. Alito ruled that the Constitution does not afford protection to the unborn.
• A 2000 challenge to New Jersey's ban on so-called partial-birth abortions. Alito struck down the law based on a recent Supreme Court decision.
Analysts are divided over the meaning of Alito's votes and his various writings while on the bench.
"I don't think these cases tell us anything about whether he would vote to overturn Roe v. Wade or not," says James Bopp, general counsel for National Right to Life. "Nor do they tell us whether he supports pro-life as a value."
But Mr. Bopp says examining Alito's approach to deciding cases can reveal what kind of justice he might become. "In these cases he didn't go beyond the issues that needed to be resolved," he says. "He wasn't trying to create law. He was just carefully following the existing law."
Bopp says Alito's style of judging is likely to carry over to his work on the high court. "He's not a rookie. He's been doing this for 15 years," he says. "That usually doesn't change. He will do the same thing as a justice."