Health Minister Edwin Poots and John Larkin, the Attorney General, have won the latest round of their battle to withhold the legal thinking behind the ban on gay men donating blood.
Yesterday an Information Rights Tribunal found that Mr Larkin and Mr Poots were entitled to keep the information secret.
"It seems unfair that a public authority engaged in litigation should have a unilateral duty to disclose its legal advice," NJ Warren, the judge who heard the case, said in a seven-page finding.
The finding can be appealed to a second-tier tribunal, and then to the Appeals Court.
The case was taken by Matthew McDermott, policy manager of the Rainbow Project, who said yesterday that he was considering all his options.
Mr McDermott had launched the request under the Freedom of Information Act and, in March, the Information Commissioner found in his favour.
Mr McDermott said: "It is hugely disappointing that the minister has used yet more public funds opposing an issue around equality, this time to keep the legal advice from the Attorney General on the blood ban secret. The decision of the High Court on the blood ban not only found that the minister acted irrationally, but also that he acted without lawful authority and in breach of the Ministerial Code."
He added: "There is also a political interest in seeing the advice as is evident from calls of various Assembly Members for the advice to be released. If the Assembly is to hold the minister to account, part of that process will be to know upon what legal advice the minister made his decision."
The Health Department said that the blood ban would remain.
"There is no ban on blood donation by gay men per se. The lifetime ban is based on sexual behaviour, not sexual orientation," a spokesperson said.
Sexually active gay men are banned for life from donating blood in Northern Ireland. A similar British ban was dropped in November, 2011. This year the High Court found in favour of a gay man who appealed the ban. Mr Justice Treacy branded it "irrational". Edwin Poots, the Health Minister, was advised by John Larkin the Attorney General. Earlier this year the Information Commissioner ordered that this legal advice be disclosed.