It was brought by Green Party TD, Patrick Costello.
The High Court's dismissed a challenge by a Green Party TD to an international trade deal between the EU and Canada.
Patrick Costello had challenged the constitutionality of the agreement, known as CETA.
He says he will take time to consider the judgement and possible next steps.
Eamonn Torsney reports:
"Green Party TD Patrick Costello had argued that ratification of CETA would have a chilling effect on the state's willingness to introduce regulations regarding the environment.
He also questioned how an 'investor court service' could be created without the agreement being put to a referendum.
In her judgment, Ms Justice Butler said the Deputy Costello had not established that ratification of CETA in the manner proposed would be clearly unconstitutional.
Reacting to the decision Patrick Costello says he will have to take time to study the judgement before deciding whether to appeal it.
In a statement he says there are significant issues in the case that need to be considered further and would benefit from being clarified by the Supreme Court."
Minister Martin Heydon Speaks As Fuel Scheme Announced
Sallins Man Part Of Intercepted Global Sumud Flotilla
One In Seven Households Unable To Afford Adequate Home Heating
Fifth Arrest Made In Connection With Fatal Edenderry Fire
Two People, Including A Teenage Boy, Arrested After Gun Incident In Ballymun
Man Charged With Fatal Assault Of Woman In Waterford
Fuel Support Scheme Announced, With Payments To Some Sectors Expected By June
Pedestrian In His 80s Dies After Being Struck By Car In Longford
