Health Minister Edwin Poots acted unlawfully over the failure to consider a senior trade unionist for a public body position, a High Court judge has ruled.
Mr Justice Treacy found in favour of a former general secretary of Nipsa who unsuccessfully applied for the Northern Ireland Social Care Council.
John Corey was turned down after being interviewed for the position specifically advertised as a trade union representative on the regulatory body.
In a legal challenge to the decision, Mr Corey's lawyers claimed Mr Poots was irrational and biased in vetoing his appointment after he became Health Minister in May 2011.
Two other processes started under his ministerial predecessor, Michael McGimpsey – for the Blood Transfusion Service and a Council for Nursing and Midwifery – had also sought trade union members. But the court was told that none were appointed by the time Mr Poots came to consider candidates.
Mr Corey served as general secretary of Nipsa, Northern Ireland's largest public sector union, from 2003 to 2010.
He has also been on the boards of the Belfast Harbour Commissioners, the Training and Employment Agency and the Staff Commission for Education and Library Boards.
In July 2011 he was appointed a member of the Northern Ireland Human Rights Commission.
He was put forward by Nipsa for the trade union post with the NISCC, which regulates the conduct of social care workers.
The department was also seeking to appoint a lay member to the body. Only this position was filled.
Mr Corey and Nipsa jointly sought a judicial review of the minister's decision not to appoint a trade unionist onto the NISCC.
Counsel for Mr Poots argued that he did not want to narrow the pool of candidates by ring-fencing the positions.
But Mr Corey's barrister rejected the explanation and claimed it was a smokescreen to hide the minister's opposition to having trade unionists on the panel.
Delivering judgment yesterday, Mr Justice Treacy acknowledged Mr Poots had a discretion to appoint whoever he wanted.
But the judge held that public law obligations generated by the published notice in the process remained in place. He ruled: "The frustration of those obligations by the minister was unlawful."
Further reasons for the verdict are to be contained in a written judgement due to be issued at a later date.
Mr Justice Treacy will then determine the appropriate remedy in the case.