Supreme Court nominee Clarence Thomas has expressed a belief in natural law and natural rights. In the overheated, brightly lit arena of Supreme Court politics, that simple allegiance has caused consternation at both ends of the political spectrum.

Some conservatives, who insist that judges should stick to the "original understanding" of the Framers and ratifiers of constitutional provisions, wonder whether Thomas might eschew "judicial restraint" and look beyond the Constitution to natural law as a primary source of principles for resolving constitutional cases.

Some liberals, who applaud when judges of their own stripe purport to discover "unenumerated" rights in background principles not spelled out in the Constitution, worry about how Thomas might exercise that prerogative. They are concerned that his ideas about what natural rights people have and when they come to have them could turn out to be distressingly different from their own.

The fretful on both the left and the right misunderstand the basic idea of natural law. Believers in natural law and natural rights hold that there are true standards or principles of morality that human beings are bound in reason to respect and that among these are norms of justice and human rights that may not be sacrificed for the sake of social utility. These beliefs should alarm neither liberals nor conservatives. While a few more skeptics and hard-core utilitarians can be found in both camps, most liberals and conservatives share a belief in "natural" (i.e., true, not merely conventional) principles of justice and right, however much they disagree about the exact content and implications of some of these principles.

If you believe that, say, slavery is inherently unjust and should therefore have been abolished regardless of who or how many people benefited from it, then you are a natural lawyer of some sort.

As Laurence Tribe, one of Thomas's most vociferous liberal critics, has conceded, the philosophy of natural law and natural rights was the philosophy of the Framers of our Constitution. And long after the founding generation had passed into history, America's greatest statesmen and moral leaders, from Abraham Lincoln to Martin Luther King Jr., continued to invoke this philosophy when they demanded the overthrow of slavery, segregation and other injustices in the name of "higher law" and "natural justice."

How odd, therefore, to declare that Clarence Thomas's belief in natural law and natural rights makes him unfit to interpret the Constitution.

Nevertheless, conservatives ask: How can someone who believes in natural law practice judicial restraint? And liberals ask: Isn't someone who believes in natural rights bound to oppose abortion and to read his opposition to abortion into the Constitution?

The answer to conservatives is simple. The existence of principles of natural justices does not entail the proposition that judges are authorized to substitute their own understanding of these principles for the understanding set out in the Constitution. True, the tradition of natural law theorizing includes elements of a philosophy of judging. Chief among these, however, is the requirement that judges recognize the limits of their own authority out of respect for the rule of law.

The scope of a judge's authority is settled not by natural law but by the constitutional allocation of political authority among the judicial and other branches of government. Belief in natural law, therefore, is perfectly consistent with fidelity to the Constitution as the supreme law of the land and with a commitment to judicial restraint.

The answer to liberals is simpler still. A belief that good law honors natural human rights does not resolve the question of what those rights are or who has them. Thomas's endorsement of natural law theory, and (contrary to some reports) even his praise for Lewis Lehrman's article applying natural law theory to the question of fetal rights, does not commit him to the proposition that laws permitting abortion are unconstitutional (or even that they are morally wrong). Natural law arguments have been made by thoughtful people on both sides of the abortion question.

For example, University of Pennsylvania Prof. Michael Moore, probably the leading exponent of explicit natural law theory among American legal scholars, vigorously defends Roe v. Wade on the very principle that abortion rights are natural rights. What Thomas praised in Lehrman's article could also be praised in Moore's writings, namely, an understanding of the Constitution as protecting true human rights and as constituting, in the words of Justice Brennan, "a grand location on human rights and dignity."

Whatever may be Thomas's view of the rights and wrongs of abortion, his commitment to natural law and natural rights neither requires nor permits him to treat the Constitution as a vehicle for imposing his own ideas about morality and public policy. A Supreme Court justice with the firm moral foundation of a belief in natural law and a responsible judicial philosophy that prevents him from confusing his own judgments of morality and policy with the mandates of the Constitution, is the best protector of law and liberty that Americans, liberal or conservative, could wish for.

The writer, a member of the Department of Politics at Princeton University, is a graduate of Harvard Law School and holds a doctorate in legal philosophy from Oxford University.