The British High Court in London is due to give its judgement today in a £21m dispute which could decide the future of Belfast shipyard Harland and Wolff.
The yard is appealing a former court ruling on a shipbuilding contract.
The dispute centres on work carried out at the east Belfast yard on the second of two drill ships which were being made for US oil firm Global Marine.
Harland and Wolff said the vessel was ready for delivery, but Global Marine refused to accept the ship, saying that it was not completed to its satisfaction.
The dispute had arisen out of an overspend on work to complete the drillships.
The Belfast yard said a final payment of £21m should be paid on the contract.
Harland and Wolff have made a claim for the full amount and argue that without that money, the yard could close and 500 jobs will be lost.
Harland and Wolff owner, Norwegian shipping magnate Fred Olsen, has previously taken a swipe at the US company, accusing it of trying to sink the yard.
Its parent company has already claimed that the shipyard made a loss of under £2m in the first three months of this year.
During that period the company had sales of only £6m.
Olsen Energy said recent contracts had reduced under-utilisation at the yard, while work on two ferries for the British Ministry of Defence builds up.
Earlier this year, it was announced that Harland and Wolff had won a contract to build parts of a new roll-on-roll-off ferry terminal in Liverpool.
In March, Harland and Wolff won an order to rebuild the Ha'penny Bridge across the Liffey in Dublin city centre.
The contracts were seen as vital to the company's survival after it laid off half of its 1,200-strong workforce in September 2000, due to an empty order book.