The Prime Minister's refusal to hold a public inquiry in to the murder of Belfast solicitor Pat Finucane was morally and legally indefensible, a court has been told.
A barrister representing Mr Finucane's wife Geraldine alleged David Cameron rejected an inquiry into claims of state collusion with the loyalist paramilitary killers over fears of criticism from elements of the Conservative Party and the right wing press in the UK.
Belfast High Court is hearing a judicial review by Mrs Finucane of the decision by Mr Cameron to rule out an inquiry into the 1989 Ulster Defence Association (UDA) shooting in the city.
Opening the case before judge Mr Justice Stephens, Barry MacDonald QC said the murder was one of the "most notorious" of the Troubles.
"It is notorious for good reason," he added. "The available evidence suggests that agents of the state responsible for law enforcement 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 'murder by proxy' whereby the state itself engaged in terrorism through the agency of loyalist paramilitaries."
The barrister added: "The decision not to hold one (an inquiry) is indefensible both morally and legally."
The solicitor's family has long campaigned for a full independent public inquiry into the murder, but Mr Cameron has insisted such an exercise would not shed any more light on the events.
A Government-commissioned review of the controversial murder published by Sir Desmond de Silva detailed shocking levels of state involvement.
That included spreading malicious propaganda that Mr Finucane was sympathetic to the IRA; one or possibly more police officers proposing him as a target to loyalists; and the mishandling of state agents inside the UDA who were involved in the murder.
While Sir Desmond found no evidence of an overarching conspiracy by the authorities to target the 38-year-old lawyer, he said the actions of a number of state employees had "furthered and facilitated'' the UDA shooting while there had also been efforts to thwart the subsequent criminal investigation.
As he accepted the report's findings in the House of Commons in December 2012, Mr Cameron reiterated an apology to the Finucane family and also pledged that the Government would examine the review in detail to identify potential lessons.
Mr Finucane was gunned down in front of his wife Geraldine and their three children inside their north Belfast home in February 1989.