The stigma of homosexuality can cause mental illness and depression, a medical expert told the High Court this week as an Irish lesbian couple attempted to get their Canadian marriage recognised in Ireland.

Giving evidence at the Dublin High Court case being taken by Drs Katherine Zappone and Ann Louise Gilligan, Dr Harry Kennedy, a consultant forensic psychiatrist, said that discriminating against homosexuality can lead to clinical depression.

He told the hearing, “The social consequences of homosexuality can give rise to stress, shame and embarrassment,”

“In a proportion of people this can give rise to anxiety and depression.”

He also outlined that research had established that a lack of social supports for homosexuals, which often resulted in a rise in subcultures, made the community more vulnerable to mental illness particularly depression.

The couple are seeking various remedies before the High Court. In particular, they are seeking a declaration that in 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.

They were married in Canada in 2003 and have used the first week of their case to declare their love for each other.

The State denies breaching their rights.

The case continues.