By a slim margin of victory, Prime Minister Gordon Brown's plan to give police the power to detain terrorism suspects for 42 days without charge passed in the British House of Commons on Wednesday.
Critics of the plan fear it will do irreparable harm to the country's civil liberties and the government's relationship with its Muslim communities.
A broad alliance of libertarians, lawyers, right-of-center lawmakers, and activists had opposed Brown's plans, claiming the draft laws are draconian, unnecessary and an affront to liberties won centuries ago.
An estimated 37 of Brown's own Labour lawmakers voted against his plans.
Blair's ex-chief legal adviser Lord Goldsmith and Britain's current chief prosecutor Ken Macdonald are among key officials who insist new police powers are unnecessary.
Goldsmith said the proposals could strain relations with Britain's Muslim communities and choke off a vital flow of intelligence to police.
Defenders of the policy say the complexity of terrorism plots makes the original 28-day detention without charge obsolete. Due to the international nature of terrorism and the likelihood that if there is evidence of a terrorism plot it is on encrypted electronic devices, advocates say police need more time.
Britain's 42-day detention without charge law, if it passes the House of Lords, will be the strictest in the Western world. Canada for instance only allows a suspect to be held for 24 hours without charge and the next closest to Britain is Australia, where police can hold suspects for 12 days. (Suspects in the United States can be held by police for two days without charge.)
The International Herald Tribune reports that opponents of the measure will take their case to the European Convention on Human Rights, "a recourse that has led to increasingly frequent rebuffs for the British government on issues affecting civil liberties."