What distinguishes marriage from other relationships? It is not set apart by its durability: unmarried partnerships can be more permanent than married ones. Children are not the sole preserve of marital relationships: in most liberal democratic states, it is just as common for children to be born to unmarried parents as to married ones. Unmarried partners cohabit and are financially dependent. They celebrate anniversaries and exchange tokens of love. Unmarried partners make commitments.

So marriage is not singled out by commitment, or permanence, or children, or love. It is also not distinguished by religion: some marriages are religious; but many aren’t. The real distinction between marriage and unmarried partnership is the role of the state. Marriage is a form of relationship recognised and regulated by the state.

When the state recognises marriage, it does three things: it defines, it endorses, and it regulates.

First, state-recognised marriage means that the state defines marriage and controls access to it. In a marriage regime, the state dictates who may marry. It determines whether marriage must be between a man and a woman, or whether same-sex marriage is allowed. It determines how many people can be married to each other. It determines whether and when divorce and remarriage are available. In a marriage regime, the state may also place religious or racial restrictions on marriage.

In making these regulations, the state determines the meaning of marriage. Is it an institution for loving couples or an instrument of religious and cultural kinship? Does it institutionalise traditional religious values, or can it encompass diversity? State recognition of marriage directly and inevitably engages the state in making complex and controversial statements about value and meaning, statements that promote some ways of life and family forms, and demote others.

Second, when the state recognises marriage, it provides public and official endorsement of the state of being married. A marriage regime includes a state-sanctioned marriage ceremony, with officials and celebrants. Obtaining a state-recognised marriage is not like obtaining a driving licence or completing a tax return: it involves a solemnified and lauded ritual in which the state is intimately involved. And so, when the state recognises marriage, it declares that marriages are special.

The third aspect of state-recognised marriage is regulation: the state provides a married couple with legal rights and duties. Unmarried people have legal rights and duties too. But state-recognised marriage involves giving married people a bundle of rights and duties concerning many areas of life. These may include financial support, parental responsibility, inheritance, taxation, migration and next-of-kinship: crucial areas of life that affect everyone, married or not.

Many of the most important rights and duties given to married people pertain to separation. Perhaps the strongest justification of state-recognised marriage is that it gives legal protection to the more vulnerable member of a divorcing couple, usually a woman. Marriage enables wives to focus on caring and domestic work at the expense of their careers, while retaining a legal entitlement to the income and assets of the family. In a marriage regime, this legal protection is often not granted to equally vulnerable members of unmarried couples. For example, in England and Wales, most people believe that there is such a thing as common-law marriage, giving unmarried cohabitants the protections of marriage. But they are wrong: common-law marriage has no legal status in England or Wales. Unmarried women who devote themselves to childcare and housework have no automatic financial rights over any family income or assets that are in their partner’s name, no matter how long-standing and marriage-like their relationship is, and this puts them in a position of serious vulnerability.

In a marriage regime, the legal rights and duties that are given to married people are given to them just because they are married, and not because they are engaging in relationship practices that create vulnerability or are unique to marriage.

Historically, marriage has been a deeply unequal institution. Each of the three aspects of state recognition have been used in ways that instigate and perpetuate a variety of hierarchies, most consistently based on gender but also on race, religion, sexuality and class.

Access to marriage has generally been limited to couples consisting of one man and one woman. Some countries have restricted access to marriage to people from certain racial or religious groups. For example, many US states had anti-miscegenation laws preventing interracial marriage, until such laws were found to be unconstitutional in the 1967 Supreme Court case Loving v Virginia.

Access controls reflect sexist, heterosexist, racist and generally inegalitarian interpretations of the meaning of marriage, with the result that the honorific aspect of marriage is also applied unequally. Only some people are granted state sanctification for their relationship, and this unequal approval has been used to devastating effect, with unmarried couples and their children subject to stigma and discrimination.

The legal rights and duties of marriage have also been profoundly gender-unequal in many countries. English law recognised the possibility of marital rape only in 1991; before then, husbands coercing their wives into sex had committed no crime. Married women in various times and places have had no legal rights to their own children, no rights to own property independently of their husbands, no rights to resist marital violence, no rights to divorce.

J S Mill described marriage as ‘the primitive state of slavery lasting on’

Parents may be permitted to authorise their children’s marriage, which typically means forcing young girls to marry older men and thus to submit to sexual abuse and rape. Child marriage of this sort happens not only in parts of the world where arranged marriage is common, such as India, Africa and the Middle East, but also in countries where the dominant form of marriage is romantic. For example, children as young as 10 have been married in the United States in recent years, under laws that allow children to be married if they have parental consent, or a judge’s approval, or are pregnant – even if they are under the age of sexual consent and therefore are pregnant as the result of statutory rape.

It is no surprise, then, that feminists have been objecting to marriage for centuries. In 1869, John Stuart Mill in The Subjection of Women described the legal institution of marriage as ‘the primitive state of slavery lasting on’. For the anarchist Emma Goldman writing in 1910, marriage was an insurance policy that a woman ‘pays for with her name, her privacy, her self-respect, her very life’, one that ‘condemns her to life-long dependency, to parasitism, to complete uselessness, individual as well as social’. In The Feminine Mystique (1963), Betty Friedan wrote about marriage as the cause of ‘the problem that has no name’ – the stultifying dependence of the white middle-class American housewife. Shulamith Firestone declared in The Dialectic of Sex (1970) that ‘love, perhaps even more than childbearing, is the pivot of women’s oppression today’. In Sexual Politics (1972), Kate Millett concluded: ‘Patriarchy’s chief institution is the family.’

These feminist critiques have particular force in times and places where women are legally subordinated in marriage. But many states (though by no means all) have reformed their marriage laws so that they are gender-equal. It is possible to have an egalitarian marriage regime, one in which wives are not legally inferior to husbands. So feminist critiques of marriage might seem anachronistic.

Yet removing misogyny from law is not the same as removing it from culture. For example, in England and Wales the marriage certificate asks for the names of the marrying couple’s fathers but not their mothers. This sexist hangover is particularly galling on Prince Charles’s marriage certificate, which lists his father’s name and rank (His Royal Highness The Prince Philip, Duke of Edinburgh) and not his mother’s (Her Majesty The Queen)! It is still the man who is expected to propose and present the ring, the woman who is expected to slim and present the dress; the man who is expected to earn the money, the woman who is expected to care for children; the man who is expected to enjoy his bachelorhood, the woman who is expected to dread her spinsterdom. In 1998, the fictional heroine Bridget Jones noted that unmarried women in their 30s are ‘accustomed to disappointing their parents and being treated as freaks by society’. Sociological research shows continuing associations between marriage and gender inequality: married women do more housework than both married men and unmarried women; married women are unhappier than married men; marriage renders women more vulnerable to some sorts of domestic violence. Marriage remains a powerful pull towards patriarchy.

In recent years, the tide has turned away from the feminist critique of marriage. In progressive circles, marriage has become fashionable again as the movement to recognise same-sex marriage has gained popular and legal support in a great many countries including the UK, the US, the Netherlands, Belgium, the Nordic countries, Spain, France, Ireland, Canada and Australia. Recognition of same-sex marriage is often referred to as ‘marriage equality’. And so same-sex marriage repeats the question of whether marriage can be equal, and how.

Rectifying the heterosexism of traditional marriage via the recognition of same-sex marriage has been a vital political advance. It both indicates and promotes increasing acceptance of lesbians and gays in the heterosexual mainstream. And granting same-sex couples the legal rights and duties of marriage goes some way towards rectifying the injustices that those couples have suffered, such as being denied recognition and protection when facing end-of-life decisions, or being unable to secure access to their children, or being refused permission to immigrate to remain together. If the state recognises different-sex marriage, then it is indeed an act of equality to include same-sex couples.

However, ‘marriage equality’ is not the same thing as ‘equality’. All state-recognised marriage, however reformed or constructed, is unequal – including reforms such as civil partnerships. Civil partnership is a significant improvement on marriage, because it signifies a decisive symbolic break from the sexist and heterosexist history of marriage. But even civil partnership, along with all state-recognised marriage, elevates marital or partnered relationships above other forms of relationships, family forms or ways of life; and all state-recognised marriage or partnership grants legal rights and duties to married or civil-partnered people that it denies to similarly situated people whose relationship lacks the relevant legal status.

It is no longer apt to regulate relationships on the assumption of marriage

State-recognised marriage means treating married couples differently from unmarried couples in stable, permanent, monogamous sexual relationships. It means treating people in sexual relationships differently from those in non-sexual or caring relationships. It means treating those in couples differently from those who are single or polyamorous. It expresses the official view that sexual partnership is both the ultimate goal and the assumed norm. It expresses the assumption that central relationship practices – parenting, cohabitation, financial dependence, migration, care, next-of-kinship, inheritance, sex – are bundled together into one dominant relationship. And so it denies people rights that they need in relation to one practice unless they also engage in all the others and sanctify that arrangement via the state.

State recognition of marriage is thus discriminatory against the unmarried. It is also anachronistic. While some people do bundle together their relationship practices into one marital relationship, most people (including married people) live more diversified lives. We typically juggle blended families, care for elderly relatives, face family separation by migration, and manage multiple financial dependencies. It is no longer apt to regulate relationships on the assumption of marriage.

State-recognised marriage thus cannot be justified on the grounds of ease or simplicity. Basing regulation on the marital norm leaves many vulnerable people and relationships unprotected. And so the state recognition of marriage can be justified only by claiming that marriage is uniquely valuable; but this, too, fails to treat unmarried people equally. Elevating marriage as the relationship form of unique value denies respect and recognition to the unmarried, whether single or partnered, and contributes towards the stigmatisation of unmarried people (particularly women) and their children.

We critics of state-recognised marriage face the task of identifying what should replace it. One popular alternative is based on contract.

From the 1980s onwards, various feminist theorists such as Marjorie Maguire Shultz, Lenore Weitzman and Martha Fineman advocated the use of relationship contracts to replace marriage. The idea is that contracts enable each couple to come to an agreement that matches their own unique circumstances and preferences. Contracts allow for equality since any people (and not just two) can contract together, regardless of sex, race or religion, and since partners can draw up contracts that reflect egalitarian commitments. Relationship contracts thus circumvent inegalitarian access to marriage and inegalitarian law within marriage.

Contracts also seem to promote liberty. Bespoke relationship contracts need not follow social norms or precedent. The parties to the relationship can enshrine any rules they like in their contract. They can contract for sexual fidelity or polyamory, for a traditional gendered division of labour or full equality, for permanence or a finite commitment. Relationship contracts can be drawn up to determine where the parties will live, whose career will take precedence when, who will perform which household tasks. Relationship contracts escape the one-size-fits-all model of marriage and allow for true freedom and diversity.

However, the apparent appeal of relationship contracts is undermined once we remember, yet again, the role of the state. When relationship contracts are proposed as alternatives to marriage, and not just as tools for open discussion within a couple about their hopes and plans, they must function legally. In other words, if relationship contracts are to replace marriage as the method for legally regulating personal relationships, they must be enforceable. And the enforcement of relationship contracts is normatively problematic.

The first problem is that, while relationship contracts can be drawn up in an egalitarian way, they can also reflect inequality and dominance. Unequal bargaining power, accompanied with cultural, religious and gendered norms about marital behaviour, can result in couples coming to profoundly unequal ‘agreements’. It would be deeply unjust if the state were to step in and enforce a contract that stipulated, for example, that the woman should perform all the housework and childcare as well as working outside the home, or one that stipulated that the husband should control all the money however earned and deny his wife adequate resources or financial independence. Such arrangements might be common in many existing marriages, but under a marriage regime they are (no longer) legally enforceable. But if such arrangements were contractual, the state would have to play a direct role in enforcing inequality.

The state uses the married couple as the default and leaves the unmarried as an afterthought

Second, the more esoteric aspects of relationship contracts are rarely suitable for state enforcement. Advocates of contracts imagine a variety of potential clauses: those ensuring fidelity, or instructing partners to take turns to move house to further each other’s career. How could such clauses be enforced? Under a liberal marriage regime, if the terms of a marriage are violated, then the only legal remedy offered is divorce. If the same were true of relationship contracts, they become largely meaningless as contracts: they simply state aspirations that may be broken without penalty. On the other hand, if a relationship contract is enforceable, then nightmarish scenarios arise. Imagine a world in which the state could force you to uproot your life, leave your job, leave your house, abandon relatives and friends and community and schools, and move cross-country to further your partner’s career. Or imagine a situation in which a stay-at-home housewife and mother has an affair after years of unhappiness, and is then required by the courts to pay a large sum of money to her wealthier partner as punishment for her sexual misdemeanour.

Contracts were advocated because they allow for bespoke and intimate agreements, but once we consider the reality of state enforcement of those clauses we move away from liberal utopia and towards totalitarian nightmare.

It is not part of my argument that the state should keep out of personal relationships altogether. There are various aspects of relationships that need regulation. The state needs to determine who owns what, who is responsible for children, and who is someone’s next of kin. And it needs measures to protect people made vulnerable by relationship practices such as financial dependence and care work, by relationship pathologies such as domestic violence, rape and abuse, and by life events such as migration and illness. In a marriage regime, the state must deal with such matters for everyone, not just those who are married. In some areas, marriage makes no legal difference, but in others the state uses the married couple as the default and leaves the unmarried as an afterthought. For example, in England and Wales, only married couples have protections from financial vulnerability on separation, exemptions from inheritance tax, and preferential treatment when migrating.

Rather than regulating via marriage, the state should regulate relationship practices. Relationship practices need regulation when they require legal determinacy or cause vulnerability. In these cases, the state should design maximally just regulation and then apply it to everyone who engages in that relationship practice. In other words, people engaging in relationship practices would not opt in to a special relationship status giving them rights and duties; they would have those rights and duties automatically, by virtue of their practices.

There are many different ways of regulating relationships, some more just than others. It is not part of my argument to settle the question of the content of relationship regulation. Even in a marriage regime, there is significant disagreement as to the rights and duties that should accompany practices such as cohabitation, migration and parenthood. My argument is simply that the state should design its regulations on the basis of relationship practices rather than status, and that it should then apply that regulation to everyone engaged in the relevant status.

To see the form of regulation I am proposing, without being distracted with dilemmas about the content of public policy, consider the following thought experiment:

What do you think is the ideal, just way of regulating unmarried people now, in a marriage regime? What laws should apply to unmarried parents, or unmarried cohabitants, or unmarried migrants, or unmarried property-owners?

However you answer these questions, it should follow that in your ideal version of the marriage-free state, the laws that you think should apply to the unmarried in a marriage regime would be applied to everyone. If you think justice requires wages for housework, then everyone who does housework should get wages. If you think justice requires exemptions from inheritance tax for those who share their primary residence, then everyone who shares their primary residence should have that exemption.

If you think that justice requires treating married people differently from unmarried people, ask yourself what it is about marriage, specifically, that justifies that difference? What relationship practice is being protected or respected? In every case, that relationship practice will be found in unmarried relationships, too. In a diverse, liberal society, one that respects the autonomy and equality of its citizens, there are no grounds for the state to recognise one specific family form above others.

The marriage-free state does not rule out weddings, or celebrations, or commitment, or stability, or family. It does not rule out love. But it does rule out the idea that these values are the preserve of one particular relationship format, and it does rule out the state elevating that relationship format above others. If the state recognises marriage, it discriminates against those who do not participate in it, and contributes towards inequality. The marriage-free state treats people and families equally.

Against Marriage: An Egalitarian Defence of the Marriage-Free State (2017) by Clare Chambers is out now through Oxford University Press.