By Dominic Casciani
BBC News home affairs correspondent
A security service image of two of the bombers, 17 months before the attacks
Inquests into the deaths of 52 people killed in the 7/7 bombings will cover the alleged failings of MI5 in the run-up to the attacks, a coroner has ruled. BBC News explains what will happen at the hearings.
What is Lady Justice Hallett's role?
Suspicious, accidental and violent deaths are investigated at inquests so that society can learn from what has happened.
In 2007, the inquests into the 52 deaths on 7 July were adjourned because three men were put on trial for allegedly helping the attackers. All three of them were acquitted last year, meaning the inquests could resume.
Lady Justice Hallett, a senior judge, was appointed to be coroner into the deaths. She held five days of hearings in April into whether the inquests should resume and what they should cover.
During those hearings, Lady Hallett heard submissions from relatives of those killed, survivors of the attacks, police forces, the emergency services and, critically, lawyers for the home secretary and security service, MI5.
So what did she rule?
Lady Hallett ruled that there should be a joint inquest into the deaths of the 52 victims because families still had many unanswered questions about when, how and where their loved ones died. That uncertainty alone, she said, was sufficient cause for resuming the inquests.
Not only will she hear evidence after the immediate aftermath of the explosions, but she will also look at the alleged intelligence failings in advance of the day.
That means she will be looking at what MI5 and counter-terrorism police officers knew about the bombers, when they knew it and whether anything could have been done to stop the attacks.
What did MI5 and the police know?
Two years after the bombings, it emerged that MI5 had come across two of the bombers on the periphery of another investigation into jihadists.
Surveillance officers saw them meeting a known extremist who was planning a bomb attack. Surveillance officers followed them to West Yorkshire and even photographed them in a motorway service station - see the picture at the top of this page.
Security officials defended the actions of officers who assessed that the pair did not present a threat to the UK. The Intelligence and Security Committee, charged with looking at the workings of MI5, concluded that the service had not failed.
Families and survivors denounced that report as a whitewash, saying that it was still not clear what MI5 had known. The former government ruled out a judicial or public inquiry and the families inevitably looked to the inquests as their best hope.
Does this mean MI5 secrets will be made public?
Lawyers for the security service warned in the pre-inquest hearing that investigating the service would encourage terrorists and was metaphorically akin to handing over the keys to Thames House, its headquarters.
Lady Hallett said she recognised that there may be national security limits on what can be examined as part of the inquest.
Will a jury rule on the deaths and alleged intelligence failings?
No. Lady Hallett will preside over the inquests. Jury inquests are held when there had been a violent death directly involving the state.
The most well-known recent example is the 2008 inquest into how armed police shot dead Jean Charles de Menezes, mistaking him for a suicide bomber.
Lady Hallett said that the circumstances of the deaths did not warrant a jury inquest. She also believed that the difficult task of examining sensitive evidence relating to MI5 could also be done more effectively without a jury.
What about survivors? Will they feature in the inquest?
About 700 people were injured in the attacks, some of them severely and for life. Nineteen survivors asked to be made interested parties to the inquest, which would have allowed them to have a lawyer in court and to question witnesses.
Lady Hallett ruled that the survivors did not meet the legal criteria to be named as interested parties, but that she expected that a great number of survivors would be giving very important testimony of what they saw and heard.
What about the inquests for the bombers?
They are being handled separately. Nobody from the bombers' families appeared or were represented at the pre-inquest hearing.
The solicitor for some of the bombers' families had initially planned to attend but did not do so after being denied legal aid funding.
What happens next?
The ball is now in the government's court. Does it accept the ruling or challenge the proposed examination of MI5 and the police? In theory, these hearings will begin in October - but the coroner has also given all parties two weeks to challenge her ruling. Any challenges may lead to the timetable slipping.