The High Court in Dublin will today rule on the validity of a lesbian couple’s Canadian marriage in London.

In a landmark case in October, the court heard arguments from Katherine Zappone and Ann Louise Gilligan claiming discriminating against homosexuality can lead to clinical depression and that the current concept of marriage is outdated.

The couple argue that failing to recognise their Canadian marriage, and in failing to apply the tax law provisions relating to married couples to them as a married couple, the State and the Revenue Commissioners have acted unlawfully, in breach of their constitutional rights to equality, to marriage, to property rights and family rights and in breach of their rights to privacy, marriage and non-discrimination under the European Convention on Human Rights.

However, lawyers for the State have insisted the pair have no right to marry under the Constitution because marriage is defined as between a man and a woman.

The couple’s lawyer, Gerard Hogan, argued that the Irish Constitution, which was made in 1937, is outdated and out of context because homosexuality is now better understood, he told the court, “If there had been a law in 1937 which had prevented people from marrying on an irrational basis, such as having red hair, being left handed or wearing spectacles, even if it was the view of the majority, that law would undoubtedly have been found unconstitutional.”

Mr Hogan also said that the vindication of the right to marry and human rights had nothing to do with a consensual argument, a point which had been forwarded by Counsel for the State when it said that the judiciary could not make a decision about a fundamental institution such as marriage without it going to the people.

He rejected the separation of powers argument put forward by Counsel for the State referring to over 90 instances where statutes had been declared unconstitutional by the Courts. The courts, he said, were not concerned with majority attitudes, they were concerned with vindicating fundamental rights.

Ms Justice Elizabeth Dunne will announced her judgement later today.