The union representing prison officers is taking action against the Corrections Department, claiming extended lockdown periods for prisoners are unsafe and are costing jobs.
The case between the Corrections Association and the Department of Corrections will be heard by the Employment Relations Authority in July.
The union's action follows a decision in January by the department to introduce a new extended lock-down policy for high-security prisoners and those on remand.
Corrections Association president Beven Hanlon says locking prisoners in their cells for longer creates unsafe conditions.
He says the policy has resulted in prisons shedding staff, but says Corrections will not provide the union with exact figures of job losses.
The department is not commenting as the matter is before the Employment Relations Authority.