The Minister for the Environment, Mr Cullen, is expected to announce his approval today of a joint consent application made by Dún Laoghaire-Rathdown County Council for the partial destruction of Carrickmines Castle.
If approved, the application would become law unless challenged during a three-week period in the Oireachtas or in new legal proceedings by conservationists seeking to protect the medieval site.
The Carrickmines Castle Preservation Group maintains that the Minister's order would be illegal under section 14 of the National Monuments Act 1930, which specifies that consent can only be granted for archaeological purposes.
The group submitted an alternative plan to the Minister last Friday. It would involve omitting the proposed South Eastern Motorway interchange at Carrickmines and "bending" the road to avoid interference with the castle's remains.