Who makes the law – judges or politicians? And whom do we trust more to safeguard our liberty and our security? In America, the separation of powers ensures that this issue has always been a perennial feature of the political landscape. In Britain, however, the judiciary has traditionally been subordinate to the legislature, symbolized by the fact that the highest court in the land is the House of Lords.

Only recently, with European courts regularly striking down acts of Parliament and judicial activism booming thanks to the incorporation of the European Convention on Human Rights into British law, have unelected judges and elected politicians been at loggerheads. And over Prime Minister Blair’s anti-terrorism laws, their rivalry has erupted into open warfare.

I found myself pondering the latest round in this slugfest in the heart of London’s legal district, the Inns of Court. A newspaper columnist and former editor of the London Times, Sir Simon Jenkins, combines his two great passions – the buildings of England and high society – by choosing a place of unusual architectural interest in which to give his annual party.

This year, Mr. Jenkins chose the former Public Record Office in Chancery Lane, where the big attraction is the Renaissance tomb of a Master of the Rolls (a very senior judge, who ranks just below the Lord Chancellor and Lord Chief Justice in the English legal hierarchy) during the reign of Henry VIII. The judge’s impressive monument is the work of Piero Torrigiani, an Italian sculptor who is remembered less for his art than for the fact that he was the man who broke the nose of a student rival, one Michelangelo Buonarotti.

The received wisdom here is that Mr. Blair must have felt like breaking quite a few judicial noses after the passage of his Prevention of Terrorism Bill provoked the bitterest confrontation between the two Houses of Parliament of modern times. You can see why Mr. Blair might have felt frustrated at the attempt by an unholy alliance of conservative peers and liberal judges to sabotage a measure that, as everybody agreed, was necessary and urgent. Last year’s Madrid bombings, which cost the prowar Aznar government the election, cast a shadow over the impending British general election, expected for May 5.

But the judges, not the terrorists, were the reason why the government needed a new anti-terror bill. Last December, the law lords, the most senior judges who sit in the House of Lords as the court of final appeal, ruled against an earlier anti-terror law passed in the aftermath of September 11, which permitted the indefinite detention of foreign terrorist suspects. Their lordships decided that the law breached the detainees’ human rights because it applied only to aliens, not to British citizens. Thanks to this judgment, about a dozen of Britain’s most dangerous terrorist suspects, including one who is alleged to have been Al Qaeda’s most senior agent in Europe, were due to be released.

Mr. Blair’s response, the Prevention of Terrorism Bill, allows for “control orders” – stopping short of imprisonment but ranging from electronic tagging to virtual house arrest – to be imposed on British as well as foreign suspects for an indefinite period. In its original form, the Bill proposed to give this power to the home secretary, subject to judicial review. This clause provoked an instant response: It was seen as a threat to habeas corpus.

Now this medieval writ, obliging the authorities to bring a prisoner before a court to be charged, embodies one of the most ancient civil rights of all. It ultimately stems from the Magna Carta and the notion that even the king is subject to the law. It is as dear to Americans as to the English. President Jefferson, in his first inaugural address, cites “freedom of the person under the protection of habeas corpus” as a fundamental liberty.

In this case, the threat was not imprisonment, but at worst, restrictions on movement and contact with others. Yet the sinister and alien notion of house arrest only reinforced a sense of unease across the political spectrum about this “un-British” bill. The public mostly supported the use of control orders, which were directed solely against Islamists of the most fanatical kind. Ordinary Britons do not care whether a suicide bomber is a British Muslim – as a small but growing number of those killed or captured in Afghanistan, Iraq, and Israel have been – or a foreigner. But the liberal elite, especially the lawyers, fear that these powers could later be used against other groups, such as animal rights fanatics or environmentalists.

There followed weeks of parliamentary trench warfare, including a vote that the government (which normally has a huge majority in the House of Commons) won only because opposition representatives failed to show up. Finally, the Labour Party in the Commons was bought off by a concession: The control orders would have to be approved by a judge in the first instance. That was not good enough for the House of Lords, which kept on throwing the bill back to the Commons. After the longest continuous session in history, lasting about two days and nights, a compromise was reached: Next fall, the act will be reviewed after the addition of a “sunset clause,” which was demanded by the opposition.

The conservative press hailed this as a blow to the prime minister’s prestige, but Mr. Blair got what he really wanted in new legal powers, with a political bonus. His Tory opponents looked opportunistic on the Iraq war, and are now looking weak on homeland security, too.

Liberty and security are inextricably connected, and the law exists to preserve both. There is a place for judges who deliberately ignore raison d’etat. But in a national emergency, human rights must give way to practical necessity. Judges undermine measures to defend the realm, the source that sustains the rule of law itself, at their peril.

Back to the Torrigiani tomb. There was another judge – a Lord Chancellor, no less – in Henry VIII’s time, whose name was Thomas More. Such was his devotion to justice that he once declared that “all were it my father stood on the one side, and the Devil on the other, his cause being good, the Devil should have right.” When More challenged the king over Henry’s break with Rome, he knew that he would pay for his defiance with his life, and he died a martyr’s death. But More never denied the king’s right to do what he did, still less to punish him. With his head upon the executioner’s block, he laid his long beard aside with the words: “This hath not offended the king.” More’s obedience to God took precedence even over his allegiance to the state, but not some abstract notion of human rights.

Our judges, so bold in their defense of human rights, are never called upon to make any sacrifice themselves, let alone lay down their lives, for their cause. Rather the contrary: Human rights have become a lucrative business for lawyers. The Pope recently declared More the patron saint of politicians. But it is the judges, at least as much as the politicians, who could learn from the example of this man for all seasons.

Mr. Johnson’s London Letter will appear in The New York Sun each week. He can be reached at djohnson@nysun.com.