There has been much debate about whether Sen. John McCain is a candidate of change. But in one area, McCain is unquestionably a reformer. He would almost certainly make fundamental changes in the direction of the U.S. Supreme Court.

    McCain has said that, should he be president, Chief Justice John Roberts and Justice Samuel Alito "would serve as the model for my own nominees." He regularly attacks what he calls "activist judging," and he described a recent ruling vindicating the right to habeas corpus as "one of the worst decisions in the history of this country." McCain has repeatedly said that Roe v. Wade was wrongly decided and should be overruled.

    If McCain is elected, change would clearly be coming to the U.S. Supreme Court. And in constitutional law, the Republican presidential nominee is anything but conservative. Once skeptical of the idea that the court should overrule Roe v. Wade, he now invokes the clichés and code words of the extreme right. His votes have matched his words, for he has been a proud and enthusiastic supporter of President George W. Bush's most extreme appointees to the courts of appeals.

    Recently McCain complained of "the common and systematic abuse of our federal courts by the people we entrust with judicial power. For decades now, some federal judges have taken it upon themselves to pronounce and rule on matters that were never intended to be heard in courts or decided by judges."

    In his view, the "system of checks and balances rarely disappoints," but "there is one great exception in our day": the Supreme Court. McCain aims to eliminate that exception. It is more than mere speculation to suggest that with judicial appointments, McCain may well follow the extreme right-wing of his party.

    The court is already dominated by Republican appointees, and in the last 20 years, it has shifted dramatically to the right. The next president is expected to be able to appoint at least one - and possibly as many as three - new members. Even a single appointment would likely shift constitutional law in major ways.

    The right to choose remains sharply contested within the Supreme Court - and the Republican Party and the pro-life movement have long sought to eliminate that right. The McCain-Palin ticket plans first to "return the abortion question to the individual states" and then "to end abortion at the state level."

    We might well return to a period in which states threatened to subject pregnant women, and their doctors, with jail sentences for exercising the right to choose. Alaska Gov. Sarah Palin opposes abortion even in cases of rape and incest, and there is no doubt that many states would attempt to enact that belief into law.

    But abortion is only the tip of the iceberg.

    Consider McCain's astounding statement that the court's recent vindication of the right to habeas corpus is among "the worst decisions" in the nation's history. (As bad as Dred Scott v. Sandford, entrenching slavery? As bad as Lochner v. New York, striking down maximum hour laws? As bad as Plessy v. Ferguson, upholding racial segregation?) McCain's favorite justices - Roberts and Alito - have consistently sided with the Bush administration in cases involving the constitutional authority of the president. Under a President McCain, their dissenting views might well become the law of the land.

    The Supreme Court has already struck down provisions of the Americans with Disabilities Act, the Age Discrimination in Employment Act and the Violence Against Women Act. A McCain court would go further. Some Republican appointees have raised constitutional doubts about provisions of the Endangered Species Act, the Clean Air Act and the Clean Water Act. With new members on the court, important environmental laws would face fresh constitutional scrutiny.

    In the last decade, Republican appointees to the bench have led a constitutional attack on affirmative-action programs. But in some areas, like education, for example, government is allowed to engage in a modest degree of affirmative action. With an appointment or two by a McCain administration, affirmative-action programs might be banned entirely.

    Does the Constitution allow Congress to enact campaign-finance reform? McCain clearly thinks so. But his favorite justices - Roberts and Alito - have severe doubts. Campaign-finance proposals already face acute constitutional doubts. With one or two McCain appointments, most such proposals may well become constitutionally unthinkable.

    All this offers merely a glimpse. Some Republican appointees want to restrict citizens' rights of access to federal courts, to give commercial advertising the same level of protection as political dissent, to provide new protection to property rights (at the expense of environmental law), to narrow the court's decisions involving sex discrimination, and much more.

    There are a major irony here. McCain calls for "strict construction" and "judicial restraint," and he rejects "legislating from the bench." But in countless areas, conservative appointees avoid strict construction, and they are all too willing to legislative from the bench.

    There is a close connection between the constitutional views of McCain's his preferred judges and the political views of the extreme right-wing of the GOP. To say the least, it would be a startling coincidence if the best interpretation of the Constitution turned out, fairly consistently, to entrench the political views of one or another side.

    When McCain calls for "strict construction" and "judicial restraint" while opposing "judicial legislation," no one should be fooled. Is it "restrained" for justices to invalidate campaign-finance laws and provisions of the Violence Against Women Act? Is it "strict construction" to strike down affirmative-action programs, to ban Congress from allowing citizens to sue in federal court, to give unprecedented protection to property rights?

    When McCain speaks of strict construction and restraint, he is speaking in code. He is signaling his desire to produce large-scale change in the direction favored by the far right - for starters, and above all, by overruling Roe v. Wade.

    It is not at all clear that a McCain administration would seek to reorient current practices in domestic arena or in foreign policy. But there is no doubt that in constitutional law, McCain favors fundamental change.

    The question remains: Is this really the change we need?

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    Cass R. Sunstein is Felix Frankfurter professor of law at Harvard Law School. He will be the Harry Kalven Visiting Professor at University of Chicago Law School in January 2009. His most recent book, which he co-wrote with Richard Thaler, is "Nudge: Improving Decisions about Health, Wealth, and Happiness." His books include "Are Judges Political? An Empirical Analysis of the Federal Judiciary" and "The Second Bill of Rights: FDR's Unfinished Revolution and Why We Need It More Than Ever."