The House of Lords may still hear an appeal against the decision not to charge any police officers over the shooting of Jean Charles de Menezes.
Jean Charles de Menezes was shot dead at Stockwell Tube station
The Menezes family had been denied a full appeal, but High Court judges have now ruled that law lords can consider legal points raised by the ruling.
The lords have the power to consider these points, and ultimately to order a full appeal, if they wish.
Mr Menezes died after being mistaken for a suicide bomber in July 2005.
The 27-year-old Brazilian electrician was shot seven times in the head at Stockwell Tube station in south London.
It was one day after an alleged attempt to detonate bombs on London's transport network, and two weeks after the 7 July terror attacks.
The Crown Prosecution Service decided last July that there was not enough evidence to bring charges of murder or manslaughter.
'Right to life'
But the Metropolitan Police commissioner is to be prosecuted under health and safety laws.
Lord Justice Richards and Mr Justice Forbes declared that the previous ruling by the High Court denying the right to appeal had raised "points of law of general public importance".
They said there were two questions relating to human rights which the House of Lords might consider answering.
The first question was whether the Code of Crown Prosecutors, which played a central role in the decision not to prosecute, is compatible with Article 2 of the European Convention on Human Rights.
The article states that "everyone's right to life shall be protected by law".
The second question deals with the correct legal tests to be applied when the High Court reviews a decision not to prosecute.