Here is a timeline of the Michael Shields case:
July 2005: Liverpool fan Shields, then 18, is convicted of the attempted murder of barman Martin Georgiev during a fight in Golden Sands, Varna, Bulgaria, on May 30.
* The teenager, who was staying in the resort after watching his team win the Champions League final in neighbouring Turkey, denied any involvement in the fracas - he says he was asleep in his hotel at the time. He is jailed for 15 years.
* Another Liverpool man, 20-year-old electrician Graham Sankey, made a confession to the attack but the evidence was ruled inadmissible at Shields' trial. Mr Sankey's solicitor later suggests it may have been an entirely different fight in which his client took part.
October 2005: Shields appears before a court in Varna to appeal against the sentence.
November 2005: The court gives its verdict, no reduction.
* Relatives and local MP Louise Ellman deliver a 70,000 strong petition to Downing Street over the case.
March 2006: Shields appears in the Supreme Court in Sofia to appeal against his conviction. His father, also Michael, says he is "hopeful" his son will be granted a retrial.
April 2006: The court reduces the sentence from 15 years to 10 years but refuses to grant a retrial.
October 2006: The Foreign Office confirms that Shields will finish his sentence in the UK. It is reported that the Bulgarian authorities refused to release him to a UK prison until a fine of £90,000 (including interest) was paid, which the family has now been able to do.
November 2006: Shields arrives in the UK to serve the remainder of his sentence.
May 2007: Judges at the European Court of Human Rights have rejected an appeal by Shields, his family says. He had claimed that his rights were violated during the trial.
November 2007: Hopes rise that he could be freed as the Bulgarian government says it is up to the British government to pardon him.
The Ministry of Justice says that in general terms pardons are only granted where the case cannot be referred to an appellate court, and where new evidence shows the individual concerned did not commit the offence.
* Mrs Ellman uses parliamentary privilege to name Graham Sankey and Steven Clare as launching the assault. She claims two men present at the attack had identified the duo, and that four new witnesses have come forward backing Shields' innocence.
December 2007: Shields has emerged from a lie-detector test "with flying colours", Mrs Ellman says.
January 2008: Bulgarian president Georgi Parvanov tells British MEP Arlene McCarthy that he will not pardon Shields.
October 2008: Shields wins the right to a judicial review of his case.
November 2008: The Bishop of Liverpool spoke of the "travesty of justice" of the case.
December 2008: The judicial review of Shields' case is heard at the High Court and two senior judges rule that Justice Secretary Jack Straw did have the "power and jurisdiction" to exercise the ancient royal prerogative of mercy in his case.
February 2009: Merseyside Police look into the facts surrounding the Shields case at the request of Mr Straw.
June 2009: Prime Minister Gordon Brown says Mr Straw would make the "best and fairest decision" he could after reviewing the papers in the case.
July 2009: Justice Secretary Jack Straw provisionally refuses an application for a pardon.