Is a U.S. Supreme Court judgeship big enough to suit Sonia Sotomayor? Or will she settle for nothing less than a seat on the Supreme Court of World Opinion?

Just two months before being tapped to replace retiring Supreme Court Justice David Souter, Sotomayor indicated she considered the rulings of foreign and international courts as persuasive when interpreting the U.S. Constitution. She would even look to public opinion polls of "the world community" to guide her thinking.

That's what she told the Puerto Rican chapter of the American Civil Liberties Union this April. Judge Sotomayor informed the island's assembly of left-leaning lawyers that it is perfectly proper - indeed, laudable - to cite foreign and international law to determine what American law means. "International law and foreign law will be very important in the discussion of how to think about the unsettled issues in our own legal system," she declared.

She went on to align herself with Justice Ruth Bader Ginsberg in "believing that unless American courts are more open to discussing the ideas raised by foreign cases, by international cases, that we are going to lose influence in the world." (Speaking at Ohio State University, Justice Ginsberg had recently alleged - and lamented - that the Supreme Court's influence around the world had waned. She attributed this to its failure to regularly utilize foreign law in its opinions. "You will not be listened to if you don't listen to others," Ginsberg admonished.)

"Enhanced global influence" trails only "improved global opinion" as the weakest justification for referencing foreign and international law to interpret the U.S. Constitution. It is argument by ego. And it prizes being popular above being right.

Unfortunately, it reflects a neediness that just won't go away.

Sotomayor's and Ginsberg's yearning for acceptance by the in(ternational) crowd is of a piece with Justice Sandra Day O'Connor's 2006 speech in which she stated that relying on foreign law "may not only enrich our own country's decisions; it will create that all-important good impression."

You can almost hear her inner child pleading "Ooh, pick me! Pick me!" It's natural to want to hang out with the cool kids, the ones with the trendy clothes, their pungent Gauloises and their languid, insouciance.

But topping the popularity charts, creating a "good impression" and influencing foreign courts is not in the job description of any U.S. judge. It's certainly not the function of our highest court.

International relations and public diplomacy are functions of the political branches of the U.S. government. Nowhere does the Constitution state or imply that the Supreme Court should function in a way so that its jurisprudence can influence foreign tribunals. Nor does the oath of office for Supreme Court Justices offer a whiff of concern for such matters. The sole duty articulated by the oath is that a judge must "faithfully and impartially discharge and perform all the duties incumbent upon (her) ... under the Constitution and laws of the United States."

Judge Sotomayor's speech reveals a yen to be belle of the ball among her international peers at law school symposia and overseas conferences. But such desires should not sway the deliberations of Supreme Court justices when deciding on cases of crucial constitutional importance.

America may very well have something to learn by studying the laws of foreign nations and examining the social practices of the international community. And when the legal and social norms of foreign lands prove compelling, they certainly may be incorporated into the American system.

But they should be incorporated through proper democratic means - i.e., by laws enacted by elected legislators.

Imposing foreign norms and practices through judicial fiat is another matter entirely. And while such an imposition may create a "good impression" among the international judiciary and within the legal professoriate, it has little to do with sound constitutional interpretation. Judge Sotomayor has not yet had occasion in her own legal opinions to rely upon foreign and international law to interpret the Constitution.

But she will have a lifetime to do so if the Senate confirms her as the next associate justice to the Supreme Court.

If she intends to rely on anything other than U.S. legal precedent and American norms in interpreting the Constitution, then Judge Sotomayor has an obligation to explain and defend her position at the forthcoming confirmation hearing.

Steven Groves oversees the Freedom Project as the Bernard and Barbara Lomas Fellow of the Margaret Thatcher Center for Freedom at The Heritage Foundation (heritage.org).