The country's top judge has overturned the convictions of five Muslim men jailed last year for downloading and sharing extremist terror-related material. The Lord Chief Justice ruled that unless there was clear evidence of "terrorist intent" it was not illegal to read or study such literature.

The prosecution of the five young Muslim men was regarded as a test case, and is likely to lead to other convictions being overturned. These include that of 23-year-old Samina Malik - the so-called "lyrical terrorist". She was the first woman to be convicted under the Terrorism Act and was given a nine-month suspended sentence in December after being found guilty of possessing terrorist manuals.

Irfan Raja, Awaab Iqbal, Aitzaz Zafar, Usman Malik and Akbar Butt were all convicted last year after becoming "intoxicated" with jihadi websites and literature.

Under the Terrorism Act 2000, a person commits an offence if he possesses an article in circumstances which give rise to a reasonable suspicion that his possession is for a purpose connected with the commission, preparation or instigation of an act of terrorism.

Prosecution lawyers have argued that simply obtaining and sharing extremist literature was an offence under the law. However, Lord Phillips ruled against this interpretation and said there had to be a direct connection between the object possessed and the act of terrorism. He added: Difficult questions of interpretation have been raised in this case by the attempt by the prosecution to use section 57 for a purpose for which it was not intended.

The ruling was welcomed by human-rights lawyers who said it safeguarded the right to freedom of speech and thought.

Imran Khan, solicitor for Mr Zafar, said: My client is over the moon. He says it is surreal and he cannot see why he has spent the last two years in prison for looking at material which he had no intention of using for terrorism. Young people should not be frightened of exploring their world. There will always be people out there with wrong intentions, but we must not criminalise people for simply looking at material, whether it is good or bad.

Prosecutors have seven days to appeal against the ruling.

A woman who wrote jihadi poetry using the pen name “Lyrical Terrorist” has had her terrorism conviction quashed by the Appeal Court.

Three senior judges said the jury at Samina Malik’s trial last year had been confused and her conviction for possessing items of use to terrorists was unsafe.

The Crown Prosecution Service indicated that it would not seek a retrial.

Miss Malik became the first woman convicted under terrorism legislation since 2001 when she was found guilty of possessing jihadi propaganda in December last year. Of 21 items found in Miss Malik’s possession, 14 were propaganda items. However, she also possessed documents including The Terrorists Handbook, The Mujahideen Poisons Handbook, and operator manuals for firearms and anti-tank weapons.

She was given a nine-month jail sentence suspended for 18 months.

Miss Malik had also penned gruesome poetry in chatrooms praising the beheading of hostages in Iraq. On the back of a till receipt she scribbled: The desire within me increases everyday to go for martyrdom.

Her conviction, under section 58 of the Terrorism Act 2000, was widely condemned as a “thought crime” by commentators and Muslim community leaders.

But it became inevitable that she would be cleared of the crime in February when the Appeal Court quashed the convictions of five men under section 58 and effectively rewrote the Terrorism Act. The court ruled then that propagandist or theological material - no matter how extreme - could not be considered of practical use to terrorists.

But Lord Phillips of Worth Matravers, the Lord Chief Justice, presiding at the Appeal Court, said her conviction was now unsafe: The jury was required to consider not only documents which were capable of being of practical utility for a person committing or preparing an act of terrorism, but a large number of documents that were not. We consider that there was scope for the jury to have become confused.