The Home Secretary today began its legal appeal to salvage one of the Government's key anti-terror measures ruled unlawful by a High Court judge last week.

Lawyers for the Home Office today accused Mr Justice Sullivan of a series of "misunderstandings and errors" when he decided that the system of control orders for monitoring terror suspects was a breach of human rights law.

The judge had ruled in a test case in April that a British man, referred to as MB, who is suspected of wanting to fly to Iraq to join al-Qaeda, was made subject to an order without a fair hearing, thus infringing Article 6 of the European Convention on Human Rights.

Mr Justice Sullivan followed this with a second ruling last week, affecting six Iraqi terror suspects who are currently subject to control orders.

Today, Ian Burnett QC, appearing for the Home Secretary, asked three appeal judges to declare Mr Justice Sullivan had got the law wrong.

Mr Burnett accused the judge of making the "surprising" suggestion that Parliament was "not competent" to legislate and give the Government powers to make control orders in the way that it had.

He said: "Taking steps to protect against risks to national security. of which protecting against terrorism is the most obvious component, is one of the first responsibilities of government.

"Taking precautionary measures on the basis of valuation of risk is part of that task."

Mr Justice Sullivan had "misapplied" the requirements of Article 6 and failed to pay proper regard to the nature of the task entrusted to the Home Secretary by Parliament.

Using "unusually strong language", he had interpreted the 2005 Prevention of Terrorism Act, which conferred powers to make the orders, "in an artificially restrictive way", argued Mr Burnett.

Because of the heatwave, barristers were given permission to take their wigs off in Court 3 of the Royal Courts of Justice as the three-day hearing got under way before three very senior judges - Lord Phillips, the Lord Chief Justice, Sir Anthony Clarke, the Master of the Rolls, and Sir Igor Judge (President of the Queen’s Bench Division).

The case is almost certain to go to the House of Lords, the highest court in the land, for a final decision.

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