Yesterday, Rowan Williams, the archbishop of Canterbury, suggested that shari’a law apply in Britain in limited circumstances. In a BBC interview, he said that it is “a bit of danger” that “there’s one law for everybody and that’s all there is to be said.” So it would be okay if, for example, marital disputes or financial matters would be tried in an Islamic court. Williams argues “a constructive accommodation with some aspects of Muslim law” will help social cohesion. (He must have had this in mind.)

Whatever happened to the concept that one law applies to everyone? In the country that greatly contributed to the concept of the West’s legal principles, there is already precedent for separate law and tribunals. The Archbishop of Canterbury noted that Britain’s Jewish community has its religious courts, the Beth Din. What’s good for Jews, Dr. Williams argues, is also good for Muslims.

So shouldn’t each person have the right to choose his or her own legal system? In the contractual setting, parties can select their own law as well as designate the court that will hear any dispute. They may even decide on arbitration—in other words, private settlement largely outside the judicial system. Yet this is voluntary, as are cases in Britain’s Jewish tribunals. “There’s no compulsion,” says David Frei, the registrar of the London Beth Din. “We can’t drag people in off the streets.” Moreover, the Jewish courts hear only civil disputes, and then only within the strictures of British law. In essence, the Beth Din is a private arbitration organization.

The risk of applying shari’a is drawing—and enforcing—the line for adherents who seek no bounds. The BBC reports that Somalis living in Britain have their unofficial courts, or “gar,” which have, without legal justification, begun to handle criminal cases. Unfortunately, Britain’s Muslims are already growing apart from the rest of society, as the Bishop of Rochester, the Right Reverend Dr. Michael Nazir-Ali, noted when he said last month that parts of England had become “no-go” areas for infidels. So the risk of introducing Muslim law is that it will, as a practical matter, become compulsory in Britain’s increasingly exclusionist and radical Islamic communities.

So I’m with the Sun, Britain’s tabloid. “It’s easy to dismiss Archbishop of Canterbury Rowan Williams as a silly old goat,” the paper said today. “In fact he’s a dangerous threat to our nation.” And Western society as well.