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Non-monogamous relationships in the UK: legal challenges and options

In the UK, monogamous family structures have long been the norm. However, the evidence suggests a growing openness to non-monogamous arrangements in British society as one of many alternative family structures. Despite this, non-traditional relationships lack legal recognition or protection and rights and responsibilities can be limited or non-existent.

Monogamy and changing social norms in the UK

Non-monogamous relationship arrangements are a feature of many cultures, both currently and historically. However, in the UK (and the West in general) the Judeo-Christian tradition and corresponding cultural norms defined the family, culturally and legally, as between a single man and a single woman. More recently, we have seen this expanded to embrace same-sex monogamous relationships.

However, commentators have observed a rise in non-traditional relationships and family structures within the UK. A recent UK study looking at polygamy (i.e., a one-sided non-monogamous arrangement) found that a third of heterosexual men and 11% of heterosexual women were open to having more than one spouse or long-term partner.). A 2023 YouGov poll found that 12% have considered non-monogamy.

These relationships can vary in structure, but all share the common feature of involving more than two people.

Current legal position

Bigamy, the act of being married or in a civil partnership with more than one person, is a crime in England and Wales, punishable by imprisonment. There is currently no legal mechanism by which more than two people can legally formalise their relationship in a way akin to a marriage, meaning that there is no similar legal protection in the event that the relationship ends.

Those in polyamorous relationships have the same legal rights as unmarried couples, with limited financial recourse if the relationship were to break down. This is the case even where there are shared financial responsibilities, assets, and children. Claims are limited to joint property (or property that an individual has an interest in) and financial provision for children under Schedule 1 of the Children Act 1989.

Options for non-monogamous relationships

Where there are shared responsibilities in the relationship, those involved may wish to enter into written agreements which outline the nature of the responsibilities during and after the relationship. Similarly to cohabitation agreements between unmarried monogamous couples, these agreements may afford those in non-monogamous some protection on relationship breakdown.

If you are in a non-traditional relationship and would like to understand your legal position or explore options for your relationship, contact Sarah Green.

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