In 1839, one woman single-handedly changed English family law. She had no legal training, no political office, and after her divorce, almost no rights to her own children. What she had was a pen and an audience. Without Caroline Norton, co-parenting as we know it today might have arrived a hundred years later.
In ancient Rome, the law was unambiguous. Patria potestas — “paternal power” — gave the eldest male in a family virtually unlimited control over everyone within it. This was not a metaphor but the letter of the law, set out in the Law of the Twelve Tables in the fifth century BCE and later developed in the codes of Gaius and Justinian.
A child had no independent legal status. Everything they earned or received as a gift automatically became the property of the father. The father could approve or forbid his child’s marriage. He could sell his son into slavery — the law permitted this up to three times, after which the son was formally freed from paternal power. None of this was abuse. It was the law.
The mother was largely absent from this system as a legal person. After a husband’s death, custody of children did not pass to her but to the next man in the hierarchy — the deceased’s brother, an uncle, or, in the case of landholding vassals, the lord.
A child was a family asset — not in any figurative sense, but in the most literal one. Their marriage was traded, their labour used, their future planned without them.
In medieval England this took a particularly formalised shape. When a vassal died leaving a minor heir, wardship passed to the lord or a person appointed by him. The guardian managed the lands and their income, decided on the child’s marriage — and all of this was a legitimate source of revenue. In 1540 Henry VIII created the Court of Wards and Liveries specifically to administer the sale of such wardships. It survived until 1646, when it was abolished during the Civil War — not out of humanitarianism, but because it had become too corrupt.
By the early nineteenth century the situation in England was somewhat better — but not by much. After a divorce, children under sixteen remained with the father by default. The mother, even if she had been the primary carer, lost all rights to her child. She could not demand visits, could not contest decisions about where the child lived, could not protect the child from the father even in the face of clear threats.
Caroline Norton was a writer, a woman of society, and someone with a sharp pen. After a painful divorce, her husband barred her from seeing their three sons. She described what was happening in a series of open letters, pamphlets and public addresses — and did so with such force that her words reached not only suffragists but conservative Members of Parliament.
In 1839 the Custody of Infants Act was passed — the first law to give mothers the right to petition a court for custody of children under seven and for regular access to older ones. It was a modest step by modern standards: the mother still had no say in education, medical care, or residence. But for the first time a court had a mandate to look beyond blood ties and consider something else.
That something else — the idea of the child’s interests — became the central principle of family law for the following two centuries.
The 1839 Act set in motion a process that by the end of the nineteenth century had produced the opposite extreme: courts began automatically awarding young children to their mothers. The so-called Tender Years Doctrine held that a child below a certain age needed above all the warmth of a mother. Courts rarely deviated from this.
In the first half of the twentieth century in the United States this sometimes reached absurd extremes. In certain states in the 1930s, courts explicitly recommended placing children with the mother “while the child is still at the breast” — a formulation sometimes applied to children as old as eighteen months. The father’s income and housing stability were not considered weighty arguments.
The pendulum had swung from “children as the father’s property” to “children as the mother’s exclusive responsibility.” Neither extreme placed the child at the centre.
The counter-argument came from an unexpected direction — psychology. John Bowlby, who developed attachment theory in the 1950s and 60s, showed that for healthy development a child needs a reliable emotional base. But Bowlby never wrote that this base could only be a mother. His work became an argument both for and against maternal preference, depending on who was reading it.
By the 1970s several forces had converged. The feminist movement demanded that women not bear the full weight of child-rearing alone. The fathers’ rights movement — symmetrically — demanded an end to their automatic exclusion from their children’s lives. Psychologists were producing data on the harm that conflictual divorces caused children.
The response was the principle of the best interests of the child, which gradually displaced all automatic presumptions. Instead of asking “who has the right to the child?” courts began asking “what is best for this particular child?”
In the United States the principle was formally endorsed by the National Council of Juvenile and Family Court Judges in the early 1970s. In Britain it found legislative expression in the Children Act 1989, which for the first time introduced the concept of “parental responsibility” and established that both parents retain the right to participate in their child’s life after separation.
While most countries were still debating theory, Sweden was running experiments. In 1976, Swedish courts were given the power to order shared physical custody — a genuine division of the child’s time between two homes — even if one parent objected. This was a revolutionary decision even by the standards of the time.
In 1992, joint custody became the default: courts awarded it automatically unless there were compelling reasons not to. In 1998 they went a step further and permitted compulsory joint custody even over one parent’s objections, if it served the child’s best interests.
The results were tracked. In 2015, Swedish researchers published findings based on surveys of around 150,000 schoolchildren. The conclusion: children who regularly lived with both parents reported significantly fewer psychosomatic complaints — headaches, sleep problems, anxiety — than peers in sole-custody arrangements. The difference was statistically robust and held even after controlling for parental income and education.
Today around a third of divorcing families in Sweden choose an equal-time model. In the 1980s that figure was one percent.
The entire journey described above concerns one situation: what happens to children when a couple separates. Co-parenting in its modern sense is a different scenario.
It is when two people consciously choose to raise a child together without being romantic partners. Not “how do we divide the child after splitting up” but “how do we together give a child what they need, from the beginning.”
This model has always existed — in extended families, in communal arrangements, in circumstances of war and migration. But as a deliberate choice it began to take shape in the late twentieth and early twenty-first century: alongside the growth in the number of single people who wished to become parents, the development of assisted reproductive technologies, and a shift in how society understands what a family is.
Co-parenting is not a Plan B after a failed relationship. It is a Plan A for those who want to build parenthood consciously from the start.
Module 1 (Matching & Co-Parenting) contains a structured list of questions for a first meeting with a potential co-parent — and an expert guide to drafting a co-parenting agreement. Verified family lawyers from multiple jurisdictions are available in the Partners section.
the ancient Roman concept of “paternal power,” giving the eldest male in a family near-absolute control over all its members, including the right to sell children into slavery.
a legal presumption of the nineteenth and twentieth centuries that young children should remain with their mother after divorce. Gradually displaced by the “best interests of the child” principle.
a principle of family law holding that any decision concerning a child must be guided by their wellbeing, not by the rights or privileges of parents. Enshrined in the UN Convention on the Rights of the Child (1989).
an arrangement in which both parents retain legal rights and/or physical time with a child after separation. Legal custody (decision-making) and physical custody (residence) are distinguished separately.
the feudal system of guardianship over minor heirs, in which a lord gained control of a child’s estate and marriage upon the death of their father-vassal.