A man who has held a five-year anti-war protest outside Parliament has left his camp to face down a new court threat.
Brian Haw has been protesting outside Parliament since 2001
Last July Brian Haw, 56, won a legal battle to continue his vigil due to a drafting error in a new law banning unauthorised protests in Westminster.
The High Court ruled in favour of Mr Haw, from Redditch, Worcestershire, who claimed he was exempt as his protest pre-dated the legislation.
The government is urging the Court of Appeal to overturn that decision.
The law states that anyone wanting to demonstrate in a half-mile zone in central London must have permission from the police when the demonstration starts.
Last year, lawyers for Mr Haw argued his demonstration had begun four years earlier and therefore he did not have to apply for authorisation.
The government said Mr Haw posed a potential security risk and described his argument as absurd.
But judges ruled by a 2-1 majority in his favour.
Since then the Serious Organised Crime and Police Act 2005 has seen several demonstrations quickly disbanded - from a cabbies' protest over proposed law changes to anti-war demonstrations.
But Mr Haw, the intended target of the new law, has remained in place, with his large display of anti-war banners, placards and flags.
On Monday David Pannick QC, representing Home Secretary Charles Clarke, told the Court of Appeal judges: "The appeal raises a short but important, and indeed interesting, question of statutory construction."
Mr Haw sleeps in the square, where he first appeared in June 2001 demonstrating against Western sanctions on Iraq.
He later began protesting against British involvement in the US-led war and its aftermath.
The appeal judges have reserved their decision. No date was given for the ruling.