A High Court judge has compelled authorities in Belfast and London to reconsider providing funds for legacy inquests.
With no Executive currently in place at Stormont, Sir Paul Girvan said his order will provide civil servants running the departments with certainty about their legal duties.
He also ruled that former First Minister Arlene Foster is liable for costs in a case where she was found to have unlawfully blocked a plan aimed at clearing a backlog of nearly 100 Troubles-related killings.
The judge said UK authorities have failed to effectively deal with delays and shortcomings in carrying out legacy inquests.
He directed the Executive Office, the Department for Justice and the Secretary of State for Northern Ireland to reconsider their duties in providing extra resources to the Coroners Service for legacy inquests.
His ruling came in a case brought by the widow of an innocent civilian shot dead along with eight IRA men.
Brigid Hughes, whose husband Anthony died after being unwittingly caught up in the SAS ambush of an IRA unit at Loughgall, Co Armagh in May 1987, challenged the failure to fund outstanding legacy inquests.
Proceedings were issued against the Secretary of State, the Stormont Executive, and Mrs Foster personally due to her alleged responsibility for the logjam.
More than 50 legacy inquests remain outstanding, with potentially 72 more cases on the Attorney General’s desk for consideration.
Although the Stormont House Agreement includes a £150m package to deal with all legacy issues, the Government has said financial resources will not be released until political consensus is reached on dealing with the past.
In 2016 a paper was drawn up by the DoJ to bid for funds based on a five-year plan devised by Northern Ireland’s Lord Chief Justice, Sir Declan Morgan, to deal with all cases.
Lawyers for Mrs Hughes went to court alleging Mrs Foster stopped it from being discussed by her Executive colleagues for political reasons.
Earlier this month Sir Paul held that the former First Minister wrongly took into account the absence of an overall agreed package to deal with outstanding issues from Northern Ireland’s violent past.
He said the DUP leader’s decision to refuse to put a funding paper on the Executive basis was unlawful and procedurally flawed.
Following Mrs Hughes’ victory lawyers returned to court to deal with costs and what further declarations should be made.
Counsel representing the Northern Ireland Office, the Department for Justice and the Executive Office argued against making an order compelling action.
Attorney General John Larkin QC also contended that the case against Mrs Foster should end without any order for costs against her.
But rejecting all those submissions, Sir Paul confirmed that First Minister, Deputy First Minister and Minister of Justice will be bound by his order of mandamus if and when they are appointed to a future Executive.
Making an order for costs against all respondents in the case, including Mrs Foster, he ruled she will also be separately liable for making earlier applications to be taken out of the case and to have him stand aside as the judge.
Outside court Mairead Kelly, whose brother Patrick Kelly was also killed at Loughgall, said: “Today’s result is of crucial importance to all those families, like ours, who have been waiting on the release of the funding needed to progress in a timely manner.
“We now urgently call upon the respective departments to enforce the order made by the court without any further delay.”