Practitioners of the loosey-goosey approach to constitutional interpretation that maddens original-meaning conservatives such as Supreme Court Justice Antonin Scalia are increasingly looking to a virtually unlimited source of new raw material: foreign law, including international human-rights conventions, Zimbabwe Supreme Court rulings, and whatever else might come in handy. Indeed, two of the more internationalist justices, Sandra Day O’Connor and Ruth Bader Ginsburg, have confidently predicted that (in O’Connor’s words) the justices "will find ourselves looking more frequently to the decisions of other constitutional courts."

The most publicized example has been Justice Anthony M. Kennedy’s majority opinion last June in Lawrence v. Texas, striking down all state laws that made gay sex a crime. In expanding the "liberty" protected by the 14th Amendment’s due process clause, Kennedy cited (among other things) a British Parliament vote in 1967 repealing laws against homosexual acts and a European Court of Human Rights decision in 1981 that such laws violated the European Convention on Human Rights.

Scalia grumped in dissent that Kennedy had ignored "the many countries that have retained criminal prohibitions on sodomy." He also invoked Justice Clarence Thomas’s assertion in a previous case that the Court "should not impose foreign moods, fads, or fashions on Americans."

But Kennedy had a plausible reason for looking abroad: The late Chief Justice Warren E. Burger’s concurrence in Bowers v. Hardwick, the 1986 decision that Lawrence overruled, had claimed that homosexual conduct had been outlawed "throughout the history of Western civilization." It was fair game for Kennedy to point out some recent history pointing in the opposite direction.

More troubling, in my view, was a 2002 decision (Atkins v. Virginia) that said imposing the death sentence on a mentally retarded murderer violated the Eighth Amendment’s ban on "cruel and unusual punishments," in part because such sentences are "overwhelmingly disapproved" by "the world community." This assertion — which Justice John Paul Stevens based on a single brief by the European Union in another case — was a transparent effort to compensate for the fact that the "national consensus" that Stevens purported to discern against executing retarded criminals simply did not exist: The laws of 20 of the 38 capital-punishment states still allowed such executions.

Also troubling was Ginsburg’s concurrence in another June 2003 decision, Grutter v. Bollinger, which upheld the use of racial preferences in university admissions. Joined by Justice Stephen Breyer, Ginsburg began by noting with approval that the International Convention on the Elimination of All Forms of Racial Discrimination allows the theoretically temporary "maintenance of unequal or separate rights for different racial groups" — a regime that Ginsburg suggested should continue for decades. Then she cited analogous provisions of the Convention on the Elimination of All Forms of Discrimination Against Women, which — Ginsburg noted in a speech a few weeks later — "sadly, the United States has not ratified."

If an international agreement that the United States has refused to ratify can be invoked as a guide to the meaning of the 136-year-old 14th Amendment, what will be next? Constitutional interpretation based on the sayings of Chairman Mao? Or Barbra Streisand?

In addition to importing foreign law to resolve purely domestic cases, Ginsburg suggested in the same speech that she wants to apply the Bill of Rights extraterritorially and enforce the "rights of any human being," anywhere in the world, in cases involving the U.S. government. She did not say whether she would carry this to the point of ordering U.S. forces overseas to give Miranda warnings to the likes of Khalid Shaikh Mohammed, the suspected mastermind of the 9/11 attacks, who was captured in Pakistan last March.

One of the charms of foreign law is that there is so much to choose from. In a 1999 dissent suggesting that a death sentence should be struck down because of a delay of more than 20 years in executing the condemned man (Knight v. Florida), Breyer cited as "useful, even though not binding," the views of the supreme courts of Zimbabwe and India, as well as the European Court of Human Rights. To be sure, the Supreme Court of Canada and the U.N. Human Rights Committee had reached the opposite conclusion. But Breyer knew which conclusion he liked.

In future cases, perhaps, justices who want to narrow the First Amendment’s guarantee of religious freedom may cite France’s recent legislation banning all students from wearing religious symbols in public schools, the main purpose of which was to strip Muslim girls of their head scarves. And the Netherlands will come in handy for any justices who want to declare a constitutional right to same-sex marriage, assisted suicide, recreational marijuana, or prostitution.

For believers in the originalist approach to constitutional interpretation, the only question in such cases should be "the understanding of the ratifiers of the Bill of Rights in 1791 [and of other constitutional provisions], not the current views of foreign nations," in the words of Robert H. Bork in his 2003 book, Coercing Virtue: The Worldwide Rule of Judges. To Bork, the foreign-law fad is simply another gambit by a Court that is determined to act as a continuing constitutional convention.

Conservatives are not alone in worrying about the dangers to our democracy of importing laws and constitutional principles crafted by intellectual elites abroad. "Since World War II, much of ‘old’ Europe has been pursuing an anti-national, anti-democratic world constitutionalism that, for all its idealism and achievements, is irreconcilable with America’s commitment to democratic self-government," writes professor Jed Rubenfeld, of Yale Law School, in the Wilson Quarterly. Rubenfeld adds, "When the international community throws down the gauntlet over the death penalty in America while merely clearing its throat about the slaughter in Yugoslavia, Americans can hardly be blamed if they see a sign that an anti-American agenda can be expected to find expression in international law."

But while it’s fun to mock the excesses of judicial one-worldism, and while it’s important to guard against the anti-democratic drift of such thinking, the trend is not all bad.

For starters, the notion of constitutional interpretation as a purely historical inquiry into the Framers’ intentions has been pretty thoroughly buried, for a long time, by the Supreme Court and the vast majority of legal scholars. Almost everybody, including Bork and Scalia, supports judicial "interpretations" that are really revisions of the Constitution in at least some cases. For better or worse, extratextual and ahistorical methods of discerning (or inventing) constitutional principles and values are the norm, not the exception.

This should not be carried to the point of imposing upon Americans the principles and values of other nations, as the Court did in Atkins. But within reasonable bounds, Supreme Court citations of foreign law can serve at least three worthwhile purposes: shedding empirical light on what might be the real-world impact of a decision following a foreign court’s approach to a common problem; enhancing the persuasiveness of the Court’s opinions to those who see international consensus as a badge of legitimacy; and displaying what Thomas Jefferson called "a decent respect to the opinions of mankind," a phrase regularly invoked by judicial internationalists.

Most of the justices regularly travel abroad and hobnob at conferences with judges, lawyers, and professors from around the world. And they regularly hear complaints like the one by a prominent London barrister, who asserted at a 2000 American Bar Association convention in London that "your system is quite certain it has nothing to learn from us," because the U.S. Supreme Court so rarely takes account of European court decisions.

Bork dismisses such complaints in his book as "insolent foreign browbeating." But there is more to them than that. We have long held out our own Constitution and our independent judiciary as models for other nations. Many of these nations have followed our example so enthusiastically that their judges regularly cite our Supreme Court’s decisions as guides to interpretation of their own constitutions. It is understandable that they should expect American justices and judges to return the compliment, at least by giving respectful consideration to their constitutional decisions even when our own Constitution requires different answers.

At a time of unprecedented fear and resentment of the United States around the globe, we desperately need all the help we can get in the war against terrorism. That alone is a good reason for the Court to take pains to show respect not only for the rule of law but also for the work of foreign and international courts. It should, in the words of Justice Ginsburg, display "a spirit of humility" vis a vis world opinion. But it should display more humility vis a vis the American electorate too.