Legal submissions ended today in the High Court challenge to the M50 motorway at Carrickmines Castle.
Ms Justice Mary Laffoy said she will make her decision on the four-day hearing next week.
The State today concluded its defence of the action by Dublin conservationist Mr Dominic Dunne, who claims part of the National Monuments Amendment Act 2004 is unconstitutional and violates EU law.
Section 8 of the Act allowed for the partial demolition and removal of the ruins of Carrickmines Castle to allow for the construction of the South Eastern Motorway - the final link in Dublin's M50 bypass.
Work will remain halted at the South Dublin site until Ms Justice Laffoy delivers her judgment on Tuesday afternoon.
Dún Laoghaire - Rathdown County Council was ordered to stop work on the controversial route on August 19th, pending the High Court hearing.
Council officials said the delay of the project, which was already dogged for two years by sit-in protests and legal battles, is costing more than €350,000 a week.