Conradh na Gaeilge is seeking a judicial review
The Stormont Executive is breaching a decade-old legal duty to implement an Irish language strategy.
That is according to a barrister representing campaigners at the Belfast High Court.
Conradh na Gaeilge is seeking a judicial review amid claims the Northern Ireland executive has done nothing about a pledge dating back to the 2006 St Andrews Agreement.
The Irish language organisation says the executive is in breach of a statutory duty, and wants a judge to order it to implement plans to enhance and protect the development of the language.
A lawyer acting on behalf of Stormont countered that there had been no inertia on the issue, and rejected a suggestion of a sham process.
Judgement has been reserved.
While Cóilín Ó Cearbhaill, president of Conradh na Gaeilge, said in a statement: "Conradh na Gaeilge engaged pro-actively with the Department of Culture, Arts and Leisure when the strategy was being consulted on, as did many others within the Irish-language community.
"We are talking about simple measures relating to children, Irish at home, visibility of the language; things that will make a demonstrable difference to the increasing numbers of people living their lives through Irish."
The case comes as former First Minister Arlene Foster has said she would not be supporting the introduction of an Irish Language Act.