Dr Katherine Zappone and Dr Ann Louise Gilligan clearly "have a long-lasting, loving relationship of mutual commitment" and had "spoken eloquently of the sense of social exclusion they feel because they are denied entry to the institution of marriage", Ms Justice Elizabeth Dunne said.
However, in this case, "the court is being asked to redefine marriage to mean something which it has never done to date".
Marriage was understood under the 1937 Constitution to be confined to persons of the opposite sex and that had been reiterated in legal decisions since, including in the Foy transsexual case in 2003, she ruled.
Some changes, she noted, had been made to the institution as it was understood in 1937, the most fundamental regarding the indissolubility of marriage.
Dr Zappone and Dr Gilligan had accepted that the common law excluded marriage between persons of the same sex on grounds of capacity and, as recently as 2004, the Civil Registration Act also prohibited marriage between persons of the same sex, the judge noted.
Dr Zappone and Dr Gilligan had relied on legal decisions from the US and Canada to argue that the Constitution is "a living instrument", Ms Justice Dunne continued.
However, many of those decisions were based on equal protection clauses and were of limited assistance given the different constitutional framework here, she found.
