Claims by three would-be bombers that their convictions over the failed July 21 plot were unfair will be re-assessed by senior European judges.
Somali nationals Muktar Said Ibrahim, Ramzi Mohammed and Yassin Omar have argued that they were denied a fair trial.
They appealed to the European Court of Human Rights (ECHR) on the basis that they were denied access to lawyers during police questioning and statements they gave were subsequently used at trial.
In December the Strasbourg court threw out their claim, finding that no prejudice had been caused to the men's right to a fair trial and there had been no violation of their human rights.
However, today the ECHR announced that the case was to be referred to its higher Grand Chamber after an application by Omar.
It means their claims will be given fresh consideration by a different group of judges.
A request to re-examine the case of a fourth claimant - Ismail Abdurahman, who was convicted of assisting one of the suspected bombers - was also accepted.
He previously claimed his trial was unfair as a statement he provided as a witness, rather than a suspect, was used against him.
The planned attack came two weeks after the 7/7 bombers killed 52 people on three Tube trains and a bus in central London in 2005.
Ibrahim, Mohammed and Omar were convicted in July 2007 of conspiracy to murder and sentenced to a minimum term of 40 years' imprisonment. The Court of Appeal subsequently refused leave to appeal against their conviction.
Abdurahman was convicted in February 2008 of assisting one of the suspected bombers and of failing to disclose information about the bombings. He was sentenced to a total of 10 years' imprisonment.
His appeal against his conviction was dismissed in November 2008 and his sentence reduced to eight years' imprisonment on account of the early assistance that he had given to the police.
At the heart of the case was the question of delaying access to a lawyer during police questioning, which took place in the aftermath of the attempted suicide bombings.
Ibrahim, Mohammed and Omar, were temporarily refused legal assistance for police ''safety interviews'' - conducted urgently for the purpose of protecting life - to be held.
The terrorists' statements during those interviews, denying any involvement in the events, were later admitted as evidence at their trial.
Unlike the other applicants, Abdurahman was not suspected of detonating a bomb and was interviewed as a witness.
He started to incriminate himself by explaining his encounter with one of the suspected bombers shortly after the attacks and the assistance he provided to that suspect.
Rather than arrest him and advise him of his right to silence and to legal assistance, police continued to question him as a witness and took a written statement from him. He was subsequently offered legal advice and consistently referred to his written statement.
This statement was subsequently admitted as evidence at his trial.