By Anna Browning
Intercept evidence has led to the arrest of terror suspects in the US
Britain's security services fear that allowing intercept evidence to be used in a court of law would undermine its work - but globally the UK's stance on this issue is an exception.
Worldwide, phone tap and e-mail evidence has convicted terror cells, war criminals and even mafia godfathers, so why has Britain been so reluctant to follow suit?
It wasn't always so. England could perhaps boast the first instance of interception being used in a court of law, when in 1586 Mary Queen of Scots was convicted of treason on the basis of intercepted mail.
And there remains a loophole in the law which allows taped conversations from prisons - mandatory for category A prisoners - to be used in evidence.
Calls Soham killer Ian Huntley made to Maxine Carr and his mother were used to secure a conviction in 2003, for example.
But despite Gordon Brown's announcement that its use will only be allowed in certain cases, elsewhere intercepted evidence is routinely used in terrorism and large-scale criminal cases.
With legal systems largely based on the English common law model, the US, Canada, New Zealand, Ireland, Australia, Hong Kong and South Africa all allow certain kinds of intercept evidence in their courts of law.
And unlike the UK a judge and not a politician has the power to authorise telephone interception in all those countries, apart from in Ireland.
According to Eric Metcalfe of legal rights organisation Justice, who is the author of several reports on the issue, in this country cases are only independently reviewed months later.
By way of contrast, in the US, the judge who authorises a phone tap in the first place, keeps the case under constant review.
Justice is a strong advocate of the use of phone and e-mail evidence, believing it would cut the needed to hold a suspect without charge.
The Lackawanna Six were jailed in 2003 for support of terrorism
Indeed, under US federal law, no-one can be held without charge for longer than 48 hours.
Phone and e-mail tapping allows US agencies to put together a case in a far shorter time, Justice argues.
"Using intercept evidence promotes freedoms in two ways," said Mr Metcalfe.
"The first is it provides much more certainty for the general public.
"They know if and when a phone tap is made on them it will have been reviewed by someone outside of government. It is a much stronger protection of our privacy.
"Secondly, it is a much more direct way of gathering evidence."
Following 9/11, the US has seen several court cases where intercept evidence has swiftly led to the arrest of suspected terrorists.
One of the first was the Lackawanna Six, a group of six Yemeni-Americans from Lackawanna, near Buffalo, who were imprisoned in 2003 for providing material to support terrorism.
The men, who had trained in the use of explosives, grenade launchers and automatic weapons at al-Qaeda's Al Farooq training camp in Afghanistan, pleaded guilty when confronted with intercepted evidence.
ALLOWING THE EVIDENCE
Australia - Attorney General issues warrants for intelligence purposes, judge for serious crime investigations. Phone calls, e-mail and mail admissible
Canada - Must apply to judge, although police can intercept communications without a warrant on an emergency basis. Phone calls, e-mail and mail admissible
Hong Kong - A three-judge panel authorises and oversees the use of covert surveillance. Only mail is admissible
Ireland - Interceptions authorised by minister for justice, reviewed by high court judge.
Phone calls, e-mail and mail admissible
Organised crime has also been hit by the use of phone evidence being used in the a court of law.
The five godfathers of New York's notorious crime families, the Genovese, Bonanno, Gambino, Lucchese and Colombo, are all serving jail terms thanks to intercepted evidence.
Intelligence expert Crispin Black believes British reluctance to use such evidence was probably because "our intelligence services are very conservative with small C".
He also wonders whether allowing phone tap evidence would perhaps reveal how reliant our security services' intelligence gathering has become on other countries, namely the US.
Meanwhile, Charles Shoebridge, security analyst and former counter-terrorism officer recalls a least one case he worked on in the 1990s where "compelling" telephone intercept evidence could not be used and the accused walk free.
He was, he says, responsible for a bombing.
"It was extremely frustrating working in this field when phone intercept evidence couldn't be used."