Breakaway train drivers group, the Irish Locomotive Drivers Association, has lost its Supreme Court bid for union recognition.
The ILDA, which halted the national rail network for three months last summer, sought the right to be recognised as a union and to have negotiating powers.
The Supreme Court held that Iarnrod Eireann was within its rights when it refused to negotiate with the ILDA as it was not an accepted body under the law.