The archbishop of Canterbury, Rowan Williams, earned an unusual rebuke from British Prime Minister Gordon Brown last week for suggesting that some version of Islamic -- "Shariah" -- law would inevitably be introduced in Britain. Even in rejecting the idea, however, Mr. Brown noted that some aspects of Shariah could be accommodated on a "case-by-case" basis.

This exchange highlights an issue that is fast reaching a boiling point in Britain and other Western countries with increasingly assertive Muslim communities. Can a modern democracy house more than one legal system, even on a limited basis, and remain a democracy as we have come to understand that term over the past two centuries?

Of course, modern Western democracies already tolerate a wide range of religious practice. That toleration is one of the fundamental attributes defining such political systems and the law very often compromises some of its rules as a result. In the U.S., for example, the Supreme Court has ruled that the Constitution permits Amish parents to end their children's formal education at the eighth grade, even though others must complete 10 or 12 years of schooling. Similarly, even in circumstances where the Constitution's "free exercise clause" does not compel it, the federal government has permitted the use of peyote (containing the hallucinogen mescaline) in American Indian rituals and also excused conscientious objectors from military service.

But there is a critical difference between permitting some flexibility for religious practices within the larger society and encouraging separate, and potentially inconsistent, legal systems for different parts of the population. Toleration suggests an exception to the norm. Interposing alternative legal rules, and institutions to administer them, creates competing norms. In effect, one part of the body politic secedes from the other parts with regard to certain aspects of national life.

Admittedly, in the past such systems have promoted civil harmony as well as civil discord. The 16th century French religious wars ended with King Henri IV's issuance of the Edict of Nantes, establishing separate legal systems in parts of France for the competing Catholic and Protestant communities. But King Henri had the advantage of a war-weary country and royal absolutism to arbitrate between these parties -- and, it is worth noting, was ultimately assassinated by an unreconciled fanatic.

For a democracy, the questions inevitably raised by separate legal systems for different religious groups are more complicated. However much a particular segment of the population might isolate itself, it must interact with individuals and entities from the larger society. In such interactions, whose rules are to prevail where there is a conflict? If the minority rules, then our notions of democracy and equality must be radically revised. If the majority is to rule, then this is not much of an accommodation.

Certainly, something can be achieved by consent. Systems of Shariah-compliant lending are already springing up in many places -- a quintessentially capitalist answer to an underserved (or unserved) market. But consent can only take things so far. Most of the difficult issues arise in areas where consent is either impossible or irrelevant. This is particularly true of family law, where advocates of a Shariah approach have been especially vocal, and where women's rights are at issue. If a father has a right to marry his daughters to men of his choosing, can the daughter object and appeal to the laws applicable in the larger community? Indeed, once subject to a Shariah system, can individuals choose to leave? Again, if the rules of the greater community permit such intervention, how much of an accommodation has actually been reached?

Other fundamental problems also arise for political participation. Should individuals subject to Shariah be permitted to participate in making laws for the non-Shariah community? That is, may they vote in elections? How can a democracy deny them; but how can a democracy permit them to make laws for others?

One thing is certain. A constitutional and legal system that does define rights based upon community identification, rather than individual citizenship, will not be democracy as we have known it. The direct and equal status of each individual citizen before the law was arguably the 18th century's greatest constitutional innovation, both in the U.S. and in Europe. The French Revolution, for example, took place when the Estates General -- representing the clergy, nobility and commonality as corporate bodies -- transformed itself into a "National Assembly," self-consciously claiming to represent directly the citizens at large.

Permitting any portion of the body politic to have its legal rights defined by community, rather than citizenship, would be a giant step backward. It is by no means clear how Western societies could practice such accommodation, even on a limited basis, without undercutting their social compact.

Messrs. Rivkin and Casey served in the U.S. Justice Department under Presidents Ronald Reagan and George H.W. Bush.


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