Gordon Brown's plans to hold terror suspects for 42 days without charge received a late boost yesterday when some of Britain's top police and security officers said the controversial proposals were "workable".
The Government is still struggling to convince several of its own backbenchers that the extension from 28 days is a proportionate response to the terror threat facing the nation. Ministers are desperate to avoid defeat when MPs vote on the measures on Wednesday.
Up to 50 Labour MPs, along with civil-rights groups, former ministers and senior legal officials have warned that the most contentious element of the Counter Terrorism Bill represents an unwarranted attack on individual freedom.
The Home Secretary, Jacqui Smith, has tried to ease fears through a series of meetings and a list of amendments designed to ensure that the powers could not be used without official scrutiny. This weekend Mr Brown stepped up the pressure with a letter to his MPs and personal calls to those believed to be considering voting against the Government.
Ken Jones, the president of the Association of Chief Police Officers, and Robert Quick, the head of Scotland Yard's specialist operations, dismissed suggestions that successive amendments to the Government's detention proposals had made them too bureaucratic to have any effect.
"We must ... reflect our unanimous view that existing proposals in relation to extending, in extremis, pre-charge detention under the terrorism legislation are workable," they declared in a letter to The Times, which was written after consultation with chief police officers and anti-terror officials across England and Wales. This is a timely endorsement from experts, as the Government prepares to argue its case this week.
But, while they confirmed the operational case for the changes, the officers stopped short of offering support: "The police service will offer operational advice to Government based on our experience and recognises the role of Parliament in exercising its judgement in balancing public safety and civil liberties."
Government whips are confident they will win on Wednesday, particularly after Ms Smith defended the plans before a meeting of Labour MPs last Monday. They insist they are not complacent, and might have to rely on the support of the nine Democratic Unionist Party MPs to shore up the Government's 65-vote majority.
The letter from Mr Brown, who can scarcely afford another setback after defeats in local elections and the Crewe and Nantwich by-election, is a final attempt to rally the troops. The Prime Minister offered no new concessions, but assured MPs that ministers had striven to balance liberty with the need for enhanced security against "individuals and groups who are prepared to use suicide attacks and want to cause mass casualties without warning".
He denied a suggestion from Thomas Hammarberg, the Council of Europe's human rights commissioner, that the plans may not be compatible with the European Convention on Human Rights. "In the legislation currently before Parliament we have done everything in our power to protect the civil liberties of the individual ... because in Britain liberty is and remains at the centre of our constitutional settlement," he told his MPs.
"The challenge has been to make sure that, through proper judicial and parliamentary oversight, we both keep the public free from the threat to our security and secure the fundamental liberties of the citizen."
Mr Brown reiterated that the terrorist threat today is "radically different" from that posed by Irish extremists up to a decade ago, because of the ability of al-Qa'ida supporters to use multiple identities, complex computer networks and operate over many countries. In 1997, 19 mobile phones, one computer and seven computer disks were seized in terrorist investigations, while in 2006 the numbers had risen to 1,620 mobile phones, 353 computers and 2,541 computer disks, he said.
How they line up
Sir Ian Blair, Metropolitan Police Commissioner: "The number of conspiracies is mounting year by year."
Jacqui Smith, Home Secretary: "A suspect could be released because of insufficient time."
Lord Carlile, terrorism watchdog: "I'm convinced that such a case may arise."
Lord Goldsmith: "It will poison the relationship between police and ethnic minorities."
Sir John Major: "Nobody has yet explained how the safeguards will work."
Counter terrorism questions and answers
What is this 42-day detention?
Ministers can already extend detention without charge for 30 days, but only under emergency powers. They want to give police the right to hold terror suspects without charge for 42 days.
Why 42 days?
Effectively, because it is the highest figure the Government thinks it can get through Parliament. Tony Blair's original plans for a 90-day detention were defeated and ministers have now settled on six weeks.
How will that work?
A chief constable and the Director of Public Prosecutions would request an extension from the Home Secretary.
How can the Government justify this?
Ministers claim it is a sensible response to new terror threats facing the country.
So, why not do it then?
Critics claim it is an unwarranted breach of human rights. Senior legal officials including Sir Ken MacDonald, the Director of Public Prosecutions, and Lord Goldsmith, former attorney general, have raised doubts over the proposals.
Lord Goldsmith was part of a Government that wanted a 90-day limit – how can he complain now the plan is 42?
Although he felt bound by collective responsibility, it was suggested that he was unhappy with Mr Blair's plan. Later, Lord Goldsmith claimed he would have felt obliged to resign if Mr Blair had pushed the 90-day limit through.