It is the ancient principle of Scots law which has spawned a sea of heartache and ended countless marriages but now adultery is facing the prospect of being scrapped altogether.
The introduction of gay marriage has raised fresh questions over its role in modern Scotland amid claims it could breach “human rights”.
Adultery can only take place between a man and woman and MSPs are being urged to back an overhaul of the law to ensure it doesn’t discriminate on the basis of gender. One leading campaign group warns it would be easier to scrap it.
But pro-marriage groups have hit back insisting this would send out a message that “faithfulness doesn’t matter”.
The first gay marriages will be held in Scotland on Hogmanay after the law was changed earlier this year. But a petition lodged with MSPs by Akri Jones says the legal definition of adultery means that even now it cannot apply to same-sex extramarital affairs.
“This is clearly infringes on the human rights of an individual, it evidences that there is no equality in adultery laws and no marriage equality in all aspects,” he states. “Gender status should not determine what constitutes adultery.”
Most divorces in Scotland now happen as a result of “unreasonable behaviour”, and this covers infidelity.
The Equality Network, which drove the campaign for same-sex marriage, warned an overhaul may be unworkable. “Our understanding is that the unreasonable behaviour basis for divorce should be sufficient to cover all kinds of sexual infidelity, including mixed-sex and same-sex acts,” a spokesman said. “Therefore, in practice, we doubt that there is a need to extend the definition of adultery. What would you include? The definition of sexual act in other law includes sexual touching with the hand through clothing, for example – should that count as adultery? The best way to do away with the anomaly, if that is felt necessary, would in our view be to abandon the specific term adultery, and deal with all sexual infidelity under unreasonable behaviour.”
Adultery now accounts for less than 1 per cent of divorces in Scotland. There were just 64 cases in 2011/12 out of 9,863 divorces.
A spokesman for Scotland For Marriage said: “Scrapping adultery would send out the message that faithfulness within marriage doesn’t matter. What a desperately sad and reckless thing that would be.”
A Scottish Government spokeswoman said the issue was considered during the passage of the Marriage and Civil Partnership (Scotland) Bill, but it was decided that “unreasonable behaviour” covered the issue so there was no change to the definition of adultery.