A woman who called herself the "lyrical terrorist" and wrote a poem about beheading a hostage, won an appeal against a criminal conviction in London on Tuesday.
Samina Malik, 23, had been convicted last year of possessing documents useful to terrorists and was given a nine month suspended sentence.
A former employee at a newspaper kiosk at Heathrow airport, she had written poetry which prosecutors said advocated violent extremism, and also downloaded Islamist literature from the Internet.
One of her poems, "How to behead", was read out in court during her trial. It contained a description in detail of how to slice off a hostage's head.
Her conviction spurred controversy, with human rights groups arguing she had been convicted of a "thought crime" without having actually done anything dangerous.
The Court of Appeal threw out her conviction on Tuesday under a ruling from February that concluded documents need to actually be helpful to a terrorist, rather than merely encouraging terrorism, for possession to count as a crime.
The Crown Prosecution Service said it would not seek a retrial after Malik's successful appeal.
"Since Ms Malik's conviction, the law has been clarified by the Court of Appeal. The result is that some of the 21 documents we relied on in Ms Malik's trial would no longer be held capable of giving practical assistance to terrorists," CPS head Sue Hemming said in a statement.
"However other documents in her possession, including 'the al-Qaida Manual', 'the Terrorist's Handbook', 'the Mujahideen Poisons Handbook' and several military manuals, clearly retain that potential. We therefore have no doubt that it was right to bring this prosecution," she said.
"Ms Malik was not prosecuted for her poetry. She was prosecuted for possessing documents that could provide practical assistance to terrorists," she added.
Hemming also said Malik had provided information on airport security at Heathrow to a man who later pleaded guilty to a terrorism offence.
The Islamic Human Rights Commission said it welcomed Malik's court victory.
"This confirms our concerns over the anti-terror laws and (their) interpretation and implementation," said the commission's chairman Massoud Shadjareh.
