The action is being taken by private investors who invested in the Irish Glass Bottle site in Ringsend in Dublin.
The judgment against Mr McNamara is being taken on foot of personal guarantees he gave in relation to borrowings of his company, Donatex.
The investors are seeking judgment against Donatex of €98m.
They claim Mr McNamara and Donatex defaulted on their agreement because they did not apply to the Dublin Docklands Development Authority for appropriate planning certificates or did not apply to Dublin City Council for planning permission within the agreed time frame.
Lawyers for Mr McNamara argue that they could not have applied for permission within the timeframe and this was known by all parties to the agreement.
Mr Justice Peter Kelly said he would try to give his decision by 21 December.
