An angry deadlock gripped the Westminster parliament for days on end last week, and through the night, until Tony Blair's government finally managed to get its latest anti-terrorist legislation through. Passions ran hot, stoked by high idealism as well as low politics.
By Barnaby Mason
UK affairs analyst
Mr Blair insisted that measures to restrict without trial the liberty of terrorist suspects - British as well as foreign - were essential in order to protect the civil liberties of the vast majority.
One rebel Labour peer argued that no one should be deprived of liberty without due process of law
The Association of Chief Police Officers backed him up. As their spokesman, Ken Jones, put it: "These are extraordinary times which call for the introduction of extraordinary measures."
For several years, the public has been bombarded by alarming headlines: "Al-Qaeda threat to blow up ships", "Will Britain be hit next?" "London faces terror attack".
It is not only Islamist terrorism that provokes this kind of fear. It is an irony of the prosperous West, where for the vast majority life has never been safer, healthier or more comfortable, that people nevertheless feel so insecure.
In Britain, there is a different scare almost every week - some serious, some not: about radiation from mobile phones, bird flu, genetic engineering ("Mutant crops could kill you!") or travel chaos from the odd snowfall.
In the terrorism debate, the government's opponents had their own deeply felt fears to express, as the unelected upper House of Parliament, the Lords, repeatedly amended the draft law.
The rebel Labour peer, Baroness Mallalieu, argued that no one should be deprived of liberty without due process of law. A former judge of Britain's supreme court, Lord Ackner, condemned the government for "a wholly unnecessary rushed approach", adding that it had brought about "the obligation to compromise some of our most serious and lasting values". Helena Kennedy said the opposition amendments were at least better than "the awfulness in the Bill".
The issue dominated the front pages of the newspapers for days
So what are the measures that ignited such passionate opposition?
Suspected terrorists, including for the first time British citizens, can be subjected to a range of control orders, as they are called. The most severe is house arrest, while others may include curfews, electronic tagging and restrictions on whom the suspects can contact, where they can go and whether they can work.
The first orders have already been imposed on a group of foreign suspects by the Home Secretary, a politician. Originally, he could act entirely on his own, but later the government conceded that a judge should be involved. A number of senior judges are less than enthusiastic about providing this judicial fig leaf.
To human rights campaigners, the whole system is designed to deny the protection of a fair and open trial. Those branded as terrorists will have no right to know what they are accused of and no opportunity to see and rebut the evidence against them.
That evidence will consist of secret intelligence and may even include information obtained by torture - provided that the torture occurred outside Britain.
The Home Secretary, Charles Clarke, dismisses as "weird" the charge that a despotic government is seeking to overturn 800 years of civil liberties dating from Magna Carta
The Home Secretary, Charles Clarke, dismisses as "weird" the charge that a despotic government is seeking to overturn 800 years of civil liberties dating from Magna Carta.
'New kind of threat'
He notes that in France and Italy, for example, an examining magistrate can hold suspects for years while carrying out an investigation. French nationals freed by the Americans from Guantanamo Bay were promptly locked up in France to little public protest.
But for British citizens in Britain, this is the first peacetime use of a form of indefinite detention without trial - except for the internment of suspected terrorists in Northern Ireland in the 1970s, which is now widely seen as a disastrous mistake.
Senior police officials say Britain is going through extraordinary times
The new legislation, even as modified and with the promise of a chance to change it in a year's time, remains deeply controversial. Some legal experts think it may be overturned by the courts, as happened with the previous law.
The government echoes President George W Bush in arguing that the country is fighting a war against a wholly new kind of international terrorism. "These terrorists," Mr Clarke said, "have enormous resources and a global reach."
It is hard for politicians to dismiss that claim, for fear that an attack will leave them open to the charge of having done nothing to prevent it.
But many people simply do no accept that Britain faces a threat to its survival as it did in World War II. And their distrust has been deepened by the invasion of Iraq.
Mr Blair justified that with intelligence about Saddam Hussein's alleged weapons of mass destruction, which turned out to be wrong. Now intelligence is to be the basis of restricting people's liberty or taking it away altogether.
That is vastly more significant than the latest bout of parliamentary ping-pong.