A High Court challenge by Aer Lingus against a ruling by the Irish Takeover Panel is to be heard by the fast track Commercial Court.
The action arises out of Ryanair's failed bid to win control of Aer Lingus. Ryanair's third bid for its rival was formally tabled in late July 2012.
In February it was blocked by the EU Commission. The Commission said the proposed merger would harm consumers by creating a dominant company on 46 routes where the carriers are currently competing.
Last month the Irish Takeover Panel ruled that if Ryanair decides to make another offer for Aer Lingus, it must wait until August of this year - 12 months after the bid was first tabled.
The Panel, which is the body responsible for monitoring and supervising takeovers and other relevant transactions in relevant companies in Ireland, prohibits bidders from making a further offer for a public company within a year of the date on which their original offer has lapsed.
Aer Lingus disputes that ruling. It says that the 12 month period starts from February when the EU Commission decided to block Ryanair's offer.
Aer Lingus will ask the Commercial Court to judicially review the decision.