A murdered Catholic lawyer was the victim of British state engagement in terrorism through loyalist terrorists, the High Court heard today.
Pat Finucane was gunned down as part of a policy of infiltrating, manipulating and resourcing paramilitary groupings to carry out "extrajudicial executions", it was claimed.
As the solicitor's family began a legal bid to force a public inquiry into the killing, a judge was told the government unlawfully reneged on such a commitment.
Counsel for the Finucanes claimed the killing was among the most notorious in Northern Ireland's bloody history.
Barry Macdonald QC said: "He was identified by State agents, including particular police officers and army officers as suitable for assassination, and he was shot dead at the behest of State agents in front of his family in a particularly brutal fashion."
Mr Finucane's widow, Geraldine, is seeking to judicially review the government over its refusal to order a full, independent probe into the killing.
The lawyer was shot dead by the Ulster Freedom Fighters at his north Belfast home in February 1989.
His killing has been surrounded by claims of security force collusion with the loyalist killers.
In December 2012, a report by lawyer Sir Desmond de Silva confirmed agents of the state were involved in the murder and that it should have been prevented.
However, it concluded there had been "no overarching state conspiracy".
The Finucane family have rejected the findings as a sham and a whitewash.
Opening the legal action in Belfast, Mr Macdonald described the murder and surrounding allegations as "an iconic case".
He quoted correspondence from one of Prime Minister David Cameron's closest advisors which described the murder of Belfast solicitor Pat Finucane as far worse than anything alleged in Iraq or Afghanistan.
In an email to another senior Downing Street official Cabinet Secretary Sir Jeremy Heywood also said he could not think of an argument to defend not holding a public inquiry, the court heard.
His views, according to Mr Macdonald, strengthened the case for ordering a full examination of the circumstances.
"An inquiry is required in this case, and the decision not to have one is indefensible both morally and legally," he said.
The barrister argued that a clear and unambiguous promise was previously made to hold such a public probe - creating a legitimate expectation on the part of the murdered lawyer's family.
"The frustration of that expectation is so unfair as to constitute a misuse of the government's powers," he contended.
"This is not a case where the competing arguments were finely balanced - the Cabinet Secretary could not think of an argument to justify the decision.
"All of the available material pointed to one conclusion, but the government arrived at the opposite conclusion."
Mr Justice Stephens was told the only explanation could be that the government had "set its mind against having a public inquiry".
According to counsel for the Finucane family, the Secretary of State's own special adviser had warned that holding such a probe would leave the administration open to attack from elements within the Conservative party and the right-wing press.
"When the decision not to have an inquiry was announced it was justified on grounds that were not only irrational but transparently false," Mr Macdonald claimed.
He was scornful of explanations at the time that the best way to get at the truth was through a review of available papers.
Everyone from Peter Cory, the retired Canadian judge who examined the case, to civil servants took a contrary view, the court heard.
The barrister insisted: "This case is one of the most notorious of the Troubles, and it's notorious for good reason.
"The available evidence suggests agents of the state devised and operated a policy of extra-judicial execution - the essential feature of which was that loyalist terrorist organisations were infiltrated, resourced and manipulated in order to murder individuals identified by the State and their agents as suitable for assassination.
"In other words, a policy of murder by proxy, whereby the state engaged in terrorism through the agency of loyalist paramilitaries.
"It's difficult to imagine a more serious allegation against a liberal democracy founded in the rule of law."
He argued that Pat Finuncane became a victim of that policy.
"He was identified by State agents, including particular police officers and army officers as suitable for assassination, and he was shot dead at the behest of state agents in front of his family in a particularly brutal fashion," Mr Macdonald continued.
"The army and police and security services have all been implicated to varying degrees in the events surrounding Mr Finucane's death and the operation of this policy that led to it."
Questions remain to be answered about the level at which that policy was authorised, and the extent to which it was known about within the government, it was claimed.
In an attempt to emphasise the seriousness of the alleged abuse of power in not holding a public inquiry, Mr Macdonald cited an email Sir Jeremy sent to Simon King, a private secretary to the prime minister, ahead of a ministerial meeting in July 2011.
In correspondence disclosed to parties in the legal case, he asked: "Does the prime minister seriously think that it's right to renege on a previous government's clear commitment to hold a full judicial inquiry?
"This was a dark moment in the country's history - far worse than anything that was alleged in Iraq/Afghanistan.
"I cannot really think of any argument to defend not having a public inquiry. What am I missing?"
A reply email stated that the prime minister "shares the view this is an awful case, and as bad as it gets, and far worse than any post 9/11 allegation", the court heard.
Mr Macdonald added: "Notwithstanding the gravity of the matters at issue, and the binding nature of the commitment to hold a public inquiry into these allegations, the government decided to renege on the commitments.
"That is a decision that can be fairly characterised as not only unlawful, but as bad as it gets in public law."
The hearing continues.