Yesterday’s Supreme Court decision in the Kernott v Jones case again highlighted the urgent need to reform the law affecting couples that live together, according to Resolution.

The Supreme Court declared that an unmarried couple’s share in property can be adjusted after they separate, provided there is evidence of a common intention to adjust ownership, or such intention can be imputed.

Resolution said that although one in six couples in the UK currently live together without being married, huge numbers of people face distress, injustice and hardship because of out-of-date laws surrounding cohabitation combined with the “common law” marriage myth. Those affected include children who were not party to their parents' decision not to marry.

In making yesterday’s judgment, both Lord Collins and Lord Wilson were critical of the continuing failure of Parliament to legislate on cohabitation.

David Allison, Chair of Resolution, said: “The fact that it has taken four different hearings in four different places to determine the outcome highlights that the law for cohabitants is a mess and is in urgent need of reform.

Despite the “common law” marriage myth, it is possible to live together with someone for decades and even to have children together, and then simply walk away without taking any responsibility for a former partner’s welfare.

That is simply wrong.

The current situation for people who live together often creates injustice and hardship, and the law fails to reflect the way people are choosing to live their lives.”

Resolution is calling for new laws for couples who have lived together for five years or more – or for less time in cases of exceptional hardship.

For cohabiting couples with children, the law would offer protection regardless of how long they have lived together.

These couples would have an automatic right to apply for certain financial orders if they separate. If a couple wished to opt out of this provision, they could do so by way of a written agreement.

Such a law would prevent injustice by allowing the courts to recognise a cohabiting relationship and decide on an outcome that is fair and reasonable.