Det Garda Noel McMahon, one of a number of Donegal-based gardaí central to the Morris Tribunal, has successfully blocked a disciplinary inquiry into alleged misconduct four years ago.
The High Court has ordered that a sworn oral investigation - which was due to have started in Letterkenny next Tuesday - be postponed pending a judicial review challenging the legality of the inquiry.
The court heard that it was a matter of public record that Det McMahon had separated from his wife following the breakdown of their marriage.
They had been living together at the time of the alleged breach of garda discipline in 1999. Then, Det McMahon phone the gardai following a row with his wife.
When two gardaí, junior to Det McMahon, arrived, he showed them a Safety Order, issued against his wife under the Domestic Violence Act.
Mr Desmond Dockery, counsel for Det McMahon, said Det McMahon had made a complaint about his wife's behaviour as a result of which she had been arrested on the strength of the Safety Order.
The disciplinary inquiry arose out of a claim by the Garda Commissioner that Det Mc Mahon had breached Garda regulations by failing to inform the arresting gardaí of a letter from the local District Court Clerk stating that the Safety Order had been issued in error.
Mr Dockery said the Commissioner was alleging the arresting gardaí had been shown the Safety Order but not the letter from the District Court Clerk. Mrs Mc Mahon had been held in custody for an hour before the matter had been clarified.
Mr Dockery told Judge Murphy he was asking for leave to seek a judicial review to quash the Garda Commissioner's decision to hear and determine allegations against Det McMahon on the grounds that the Commissioner had been guilty of excessive, unjustified and inexplicable delay in dealing with the matter.
Mr Justice Murphy said the court was satisfied Det McMahon had made out "an arguable case" and granted leave to seek a judicial review.