Former Prime Minister David Cameron was legally entitled to rule out a public inquiry into the murder of Belfast lawyer Pat Finucane after taking office, the Court of Appeal heard Wednesday.
Senior judges were told a "shifting public interest kaleidoscope" of costs and the passage of time gave him the right to reconsider pledges made by a previous Labour administration.
The murdered solicitor's widow, Geraldine Finucane, is seeking to overturn a finding that Mr Cameron acted lawfully in refusing to hold a public inquiry into the killing.
Mr Finucane was gunned down by loyalist paramilitaries at his north Belfast home in February 1989.
His family have campaigned for a full examination of alleged security force collusion with the killers.
In 2011 Mr Cameron decided against ordering a public inquiry, and instead commissioned QC Sir Desmond de Silva to review all documents relating to the case and produce a narrative of what happened.
Sir Desmond's report 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 rejected the findings as a whitewash and accused the government of unlawfully reneging on previous commitments.
Pledges to set up such a tribunal, based on the recommendation of retired Canadian judge Peter Cory, were made by a former Labour government in 2004 and reaffirmed in the following years, it was contended.
Last year a High Court judge held that Mrs Finucane had received a clear and unambiguous promise of an inquiry.
But he backed the Government's case that other public interest issues, including political developments in Northern Ireland and the potential financial pressures of a costly inquiry, were enough to frustrate her expectation.
Despite throwing out Mrs Finucane's legal bid to force the authorities to publicly examine her husband's killing, the judge also said the State has not fully met its human rights obligation to investigate.
Appealing that verdict, counsel for the family claimed the case was about an abuse of power.
It was claimed that the solicitor was the victim of an army-run death squad normally associated with Latin American dictatorships.
His murder was due to covert, state-sponsored terrorism and represents a "horror story" for the British Government, the court heard previously.
The 500 page de Silva report, which highlighted the connection of law enforcement elements to the murder conspiracy, was said to contain only five pages on the role of the Government.
No responsibility has been attached to any government minister or official, and no charges have been brought against any police officers, soldiers or security service personnel, according to the Finucanes' case.
Counsel for the Government, James Eadie QC, responded today that for any change of policy to be unlawful it must be so unfair as to amount to an abuse of process.
He pointed out that any promise to hold a public inquiry stemmed from proposals first raised at the Weston Park political negotiations in 2001.
Arguing that no commitment was given to the form or process of any such tribunal, the barrister insisted it was not an open-ended pledge.
He questioned whether it could be maintained 10 years later, following changes in government, policy and fiscal positions.
"The money appears to have run out," Mr Eadie explained.
Setting out reasons for the change of view, he said: "Very considerable time had elapsed by the time the decision ultimate had to be taken."
Lord Justice Gillen, Mr Justice Deeny and Mr Justice Horner were also given details of the family's resistance to an inquiry set up under legislation which put restrictions on disclosure.
"All of that wrangling led to enormous delays, with all of the accompanying shifting of the public interest kaleidoscope," Mr Eadie said.
"By 2010 there's been a change of government and they are constitutionally and legally entitled to review a decision (taken) by a previous administration.
"The public interest features had moved on."
Asked at one point by Lord Justice Gillen what the government's position would be if Mrs Finucane indicated now that she would accept the inquiry format, he replied: "The answer I'm pretty certain would be no.
"Time has moved on, de Silva has happened and the world has changed."
The appeal continues.
The British Government failed today in a bid to have murdered Belfast solicitor Pat Finucane's widow left to pick up the bill for her legal action over being denied a public inquiry into the killing.
Will we ever be able to put talk about dealing with the past behind us? Monday night's RTE Prime Time investigation into collusion and worse between loyalist paramilitaries and elements of the security forces suggested that we are now embarked on another twirl around the mulberry bush, with little grounds for optimism that, this time, we will arrive at any better place.
Last week was a bad week for our Protectors. It kicked off with the shameful details of the De Silva report, which concluded that the Belfast solicitor Pat Finucane had been murdered with British state collusion.