Adultery is one of the four facts by which irretrievable breakdown of a marriage can be established in Scotland. Its legal definition is narrower than most people expect, and relying on it is very often the wrong tactical choice even where it plainly happened. This guide explains what adultery means in law, what has to be proved, and when a different route will serve you better.
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Legal review: Brian Rooney, Managing Partner and Law Society of Scotland Accredited Specialist in Family Law. Last reviewed: 20th July 2026.
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The point most people get wrong. Adultery is not a “ground” for divorce in Scotland. There are two grounds: irretrievable breakdown of the marriage, and the issue of an interim gender recognition certificate. Adultery is one of four facts by which irretrievable breakdown can be proved.
The distinction matters, because it explains why proving adultery does not by itself get you a better financial settlement. See our page on grounds for divorce in Scotland.
Why Instruct Rooney Family Law
Founding on adultery invites a defence, requires proof, and rarely improves the outcome. Knowing when to use it, and when to use something else, is the advice that saves both money and distress.
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The Legal Definition of Adultery in Scotland
Irretrievable breakdown is established where, since the date of the marriage, your spouse has had sexual intercourse with another person of the opposite sex. The legal definition is deliberately narrow. Other forms of infidelity, including a sexual relationship with someone of the same sex, are not adultery in law, although they will usually support a case founded on unreasonable behaviour instead.
The same definition applies in same-sex marriages. A spouse in a same-sex marriage may rely on the other spouse’s adultery where that statutory definition is satisfied, and sexual conduct falling outside the definition may instead be relevant to unreasonable behaviour.
Only your spouse’s adultery
You cannot found a divorce on your own adultery. Only the other spouse’s conduct will do.
Emotional affairs are not adultery
An affair without intercourse, however damaging, falls outside the definition. It may well found a case on unreasonable behaviour.
No separation period is required
Unlike the separation facts, adultery allows an action to be raised immediately, without waiting one or two years.
Condonation and connivance
Adultery cannot be relied upon where it has been condoned or connived at, meaning forgiven or encouraged.
The three-month rule. Continuing or resuming living together after learning of the adultery does not, by itself, amount to condonation. However, if you go on living with your spouse beyond three months from the point at which cohabitation continued or resumed with knowledge of the adultery, the law treats the adultery as condoned and it can no longer found the divorce.
This is not a general deadline for raising proceedings. It is a rule about living together after discovery. The statutory wording is technical, and the effect can depend on precisely when cohabitation continued or resumed and when knowledge or belief of the adultery arose. If you have learned of an affair and are still under the same roof, take advice promptly.
Proving Adultery
Adultery must be admitted or proved. In practice the great majority of cases proceed on an admission, because contested proof is expensive, intrusive and rarely worth the cost.
Where it is admitted
The defender confirms the adultery, usually in a written form lodged with the court. The action then proceeds as an undefended divorce, with evidence given by affidavit and no hearing to attend.
Where it is denied
You must prove it, and suspicion is not enough. Direct evidence is rare, so cases turn on circumstantial evidence from which the court can properly infer that intercourse took place. That is a demanding and costly exercise.
The practical alternative
Where adultery is denied, the same conduct will almost always support an action founded on unreasonable behaviour, which is easier to establish and attracts less resistance. That is usually the sensible course.
Does Adultery Affect the Financial Settlement?
Almost never. Financial provision on divorce is determined under the Family Law (Scotland) Act 1985 by reference to the matrimonial property and the statutory principles, not by reference to who was at fault for the marriage ending. A spouse who commits adultery does not thereby forfeit a share of the assets.
Conduct becomes relevant only in narrow circumstances, principally where it has had a direct financial effect. Where a spouse has dissipated matrimonial funds on an affair, that spending can be taken into account as a special circumstance in deciding what fair sharing requires. It is the financial consequence that matters, not the infidelity itself. See our page on financial provision.
Nor does it affect the children. Arrangements for children are decided on the welfare of the child. A parent’s adultery is not, by itself, relevant to whether they should have residence or contact, and running that argument tends to damage the parent making it. Our children and family law section explains how these decisions are actually made.
Should You Use Adultery At All?
It is worth being blunt about this. Founding on adultery names a third party, invites denial and defence, requires proof if disputed, and delivers no financial advantage. In most cases where the marriage has ended because of an affair, a better route exists.
Available immediately, no separation period, and the conduct surrounding an affair will normally satisfy the test. Usually the pragmatic choice where a divorce is needed now.
One year’s separation, with consent
If you have been apart a year and your spouse will consent, this is the least contentious route of all, and it may open the simplified procedure if there is nothing financial outstanding.
Two years’ separation
No consent required. Slower, but entirely uncontroversial and difficult to defend.
When adultery is right
Where it is admitted, a divorce is needed promptly, and the parties are content to proceed on that basis. In that situation it is straightforward.
The Process
An action founded on adultery proceeds as an ordinary divorce. The simplified procedure is not available, because it can only be used on the separation facts. An initial writ is lodged and served, and if undefended, evidence is given by sworn affidavit without any court appearance.
The person with whom the adultery is alleged to have taken place does not have to be named, and in most cases is not. Our fee for a straightforward undefended ordinary divorce is £1,550, all in. Negotiating a financial settlement is separate work charged on a time basis in three-minute units. Read more about how our fees work.
Common Questions About Adultery and Divorce
Is adultery a ground for divorce in Scotland?
Strictly, no. There are two grounds: irretrievable breakdown of the marriage, and the issue of an interim gender recognition certificate. Adultery is one of four facts by which irretrievable breakdown can be established.
What counts as adultery in Scots law?
Sexual intercourse between your spouse and another person of the opposite sex, since the date of the marriage. The definition is narrow: an emotional affair, or a sexual relationship with someone of the same sex, is not adultery in law, although either will usually support an action founded on unreasonable behaviour.
Does adultery mean I get more in the settlement?
No. Financial provision is determined under the Family Law (Scotland) Act 1985 by reference to the matrimonial property and the statutory principles, not by fault. Conduct becomes relevant only where it has had a direct financial effect, for example where matrimonial funds were dissipated on the affair.
We are still living together. Can I still use adultery?
Possibly, but there is a time limit. Continuing or resuming living together after learning of the adultery does not by itself amount to condonation, but if you go on living together beyond three months from the point at which cohabitation continued or resumed with knowledge of the adultery, the law treats it as condoned and it can no longer found the divorce. Take advice promptly.
Do I have to name the other person?
No, and in most cases they are not named. Naming a third party adds cost and conflict without improving the outcome.
What if my spouse denies it?
You would have to prove it, and suspicion is not enough. Direct evidence is rare, so contested cases depend on circumstantial evidence, which is expensive and intrusive. In practice the sensible course is usually to found on unreasonable behaviour instead, which the same conduct will normally support.
Can I use the simplified procedure if there has been adultery?
No. The simplified procedure is only available on the separation facts. An action founded on adultery proceeds as an ordinary divorce, for which our fee is £1,550, all in, where it is undefended and straightforward.
Does adultery affect arrangements for the children?
No. Decisions about children are made on the welfare of the child. A parent’s adultery is not by itself relevant to residence or contact, and raising it as an argument tends to reflect poorly on the parent making it.
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