The family of Jean Charles de Menezes have lost a human rights challenge against the decision not to charge any individual police officer over his death.
A case brought by relatives of the Brazilian, who was mistaken for a suicide bomber and shot dead by marksmen on a London Tube train more than a decade ago, was rejected by European judges.
Lawyers for the family argued the assessment used by prosecutors is incompatible with Article 2 of the European Convention on Human Rights, which covers the right to life.
However, the European Court of Human Rights' Grand Chamber found there had been no violation.
Mr de Menezes's cousin Patricia da Silva Armani said the family are "deeply disappointed".
She said: "We had hoped that the ruling would give a glimmer of hope, not only to us, but to all other families who have been denied the right to justice after deaths at the hands of the police.
"We find it unbelievable that our innocent cousin could be shot seven times in the head by the Metropolitan police when he had done nothing wrong and yet the police have not had to account for their actions.
"As we have always maintained, we feel that decisions about guilt and innocence should be made by juries, not by faceless bureaucrats and we are deeply saddened that we have been denied that opportunity yet again."
The case centred on an argument that the test applied by the Crown Prosecution Service when determining whether charges should be brought - that there should be sufficient evidence for a "realistic prospect" of conviction - is too high a threshold.
However, the Strasbourg court's judgment concluded that "it cannot be said that the domestic authorities have failed to discharge the procedural obligation under Article 2 of the Convention to conduct an effective investigation into the shooting of Mr de Menezes which was capable of leading to the establishment of the facts, a determination of whether the force used was or was not justified in the circumstances and of identifying and - if appropriate - punishing those responsible".
It found Article 2 did not require the test to be lowered in cases where deaths occurred at the hands of state agents.
The court considered that all aspects of the authorities' responsibility for the shooting had been thoroughly investigated.
The decision not to prosecute any individual officer was "due to the fact that, following a thorough investigation, a prosecutor considered all the facts of the case and concluded that there was insufficient evidence against any individual officer to meet the threshold evidential test in respect of any criminal offence," the judgment added.
The complaint also challenged the domestic definition of self-defence but the court found the test applied was not significantly different from its own standard.
The Justice4Jean campaign said the ECHR ruling "fails not only the family of Jean Charles de Menezes but all families seeking accountability after deaths at the hands of the state".
Family solicitor Harriet Wistrich expressed disappointment at the decision but noted that four of the 17 judges dissented.
Mr de Menezes, 27, was shot dead by Metropolitan Police firearms officers at Stockwell Underground station in south London on July 22 2005.
The following year the CPS announced that no individual should be charged. In 2007 the Met was fined £175,000 after being convicted of breaching health and safety laws.
An inquest jury later rejected the police account of the shooting and returned an open verdict. The coroner had already ruled out a verdict of unlawful killing.
In 2009, the family of the electrician agreed an undisclosed settlement with Scotland Yard.
A government spokesman said it "considers the Strasbourg court has handed down the right judgment", adding: "The facts of this case are tragic, but the Government considers that the court has upheld the important principle that individuals are only prosecuted where there is a realistic prospect of conviction."