With Elena Kagan’s confirmation hearings well underway, her approach to foreign law remains an important concern.

In recent years, Supreme Court justices have increasingly looked to the laws of other nations when interpreting the United States Constitution -- a practice detrimental to the American principle of self-government. Senators should vigorously question Kagan to determine whether she too would sacrifice our sovereignty to the whims of foreign opinion, especially selective foreign opinion.

Kagan’s statements so far are troubling. In a letter written to Senator Arlen Specter before her Solicitor General confirmation, she wrote, “There are some circumstances in which it may be proper for judges to consider foreign law sources in ruling on constitutional questions.” As an example, she discussed the Eighth Amendment “cruel and unusual punishment” line of cases.

But she did not clarify when it might be appropriate to look to foreign law and when it wouldn’t be. In fact, neither has the Supreme Court. The justices who cite it have been curiously selective in their use of it and have never even hinted at a principle behind their cafeteria counter approach.

Yet it’s clear from their jurisprudence that the principle is a political one: some justices look beyond our borders only when doing so would bolster their desired result.

The Court’s habit of looking to world opinion when interpreting the Eighth Amendment’s prohibition on cruel and unusual punishment is a troubling example of things to come. In 2005, the Court used foreign standards as one of three factors leading to its conclusion that executing a 17-year old murderer amounts to cruel and unusual punishment. Foreign laws were considered in the Court’s misguided evaluation of the “evolving standards of decency that mark the progress of a maturing society.” Contemporary foreign laws were apparently more relevant than the Clause’s text or original public meaning in America, to which the Court did not dedicate even a sentence.

The Court looked to foreign law again -- albeit to a lesser degree -- in an Eighth Amendment case this term to determine that juvenile non-homicidal offenders cannot receive life without parole sentences. Before the Supreme Court imbued the Eighth Amendment with foreign law, both of these purely domestic criminal justice issues were decided by the people of the United States through the democratic process.

It’s interesting that the judges find foreign law to be indispensable in the Eighth Amendment criminal law context, yet completely irrelevant in other areas of criminal law. For example, our Exclusionary Rule, the mandatory omission of illegally obtained evidence in court, has almost no parallel in the rest of the world. Yet the justices did not see fit to consider this foreign consensus when they ruled that all states must enforce the Rule. If the Court was “guided” to abolish the death penalty for juveniles based in part on foreign law, then why not the Exclusionary Rule? The answer is that justices don’t turn to foreign law for “guidance;” they turn to it for justification.

Justice Stephen Breyer, a regular defender of the practice of citing foreign law, says it’s particularly useful to do so when considering human rights issues. In fact, “advancing human rights” is often the siren song of other justices who defend the practice. Yet these justices do not always put this supposed principle into practice.

Take the issue of abortion -- a human rights issue to those on both sides of the debate. Justice Antonin Scalia has pointed out that the Court said “not a whisper” about foreign law in its recent abortion cases. Perhaps this is because the United States is one of only six countries that have embraced a right to abortion on demand at any point prior to viability.

At the heart of this practice is an unsettling disregard for the bedrock American principles of separation of powers and self-government. The people’s representatives may look to foreign countries while crafting laws in order to see how other nations have addressed similar policy problems. Judges, on the other hand, shouldn’t try to devise solutions for such problems. Their role is to apply the laws and hold them accountable to the Constitution.

In order to determine whether Elena Kagan might be the next justice to wield the tool of foreign law, senators must dedicate considerable efforts to probing her views on this most important issue. Their duty to uphold and defend the Constitution requires nothing less.

Deborah O'Malley

Deborah O’Malley is a Research Associate in the Center for Legal and Judicial Studies at The Heritage Foundation. Follow Heritage's continuing coverage of the Elena Kagan nomination.