The Supreme Court has rejected an application by the Pro Life Campaign to be heard in an appeal on the rights of the unborn child.
The group had argued that it had amassed relevant legal expertise over the past 25 years of campaigning that would help the court.
But the three judges rejected the application, saying it was clearly being made against the background of an incipient referendum campaign.
The State had opposed the application.
In opposing the application on Tuesday, the State warned it had concerns about one particular group being elevated as an amicus.
Mary O'Toole SC said the Pro Life Campaign is a campaign group set to campaign in the likely referendum, and any application would have to be viewed with utmost caution.
The judges said allowing the Pro Life Campaign to join proceedings would lead to a blurring of distinction between legal and broader arguments.
The appeal, which could have ramifications on the referendum itself, will be heard later this month.
Caroline Simons from the Pro Life Campaign gave her reaction outside court: "Obviously disappointment - we had hoped that we would be admitted to these proceedings in order to ensure that the widest and most generous articulation of women's and baby's rights would be articulated in this case".