Why the words for shared care change at every border

Even English-speaking countries don't agree on the words

Canada's Department of Justice, reviewing custody research for a 2004 policy paper, noted that Australia, England and Scotland had already dropped the terms "custody" and "access" altogether, replacing them with language meant to describe the child's living arrangements rather than which parent had "won." The report's broader point still holds: research on shared custody or co-parenting cannot be assumed to describe comparable arrangements, because the terms are used far more loosely than any single legal definition allows.

The inconsistency runs deeper than vocabulary. Canada's own Federal Child Support Guidelines define shared custody as each parent having the child at least 40 percent of the time; a widely cited Stanford research classification used a 29 percent threshold for the same word. A statutory guideline and an academic study, working from the same research tradition, drew the line in two different places.

Where "residence" splits from "custody"

Nordic systems tend to separate the question into two: who holds parental responsibility (decision-making authority) and where the child is registered as living (residence status). Norway's 2020 government review of the child law, NOU 2020: 14, spends an early chapter just distinguishing fast bosted (fixed residence with one parent) from delt bosted (shared residence), and is explicit that the distinction has little to do with how the week is actually split. A child can spend close to equal time in each home while one parent still holds fast bosted status, with the decision-making weight that comes with it.

Germany frames the same underlying question differently again. Residenzmodell describes a child living mainly with one parent, who makes most day-to-day calls; Wechselmodell describes something closer to an even time split between the two homes. Where Norway's terms track legal authority, Germany's track something closer to a lived schedule.

Shared residence vs. primary residence — what is the difference?

The US variant: naming the parent instead of the status

US family law usually splits custody into legal custody (decision-making) and physical custody (where the child lives), then names a parent rather than a status: the "primary residential parent" is the one holding primary physical custody, typically the parent whose address the child uses for school enrolment. It is a small but real shift in framing: European systems more often describe what the child's residence is, while US terminology more often describes which parent holds it.

The distinction sounds academic until it meets a school registration form, a benefits application, or a passport office that wants a single "primary address" on file. Shared residence in the European sense and joint physical custody in the US sense both assume the child genuinely lives in both homes; both still tend to collide with administrative systems built to record one address.

The vocabulary keeps shifting, even within one country

England and Wales offer a useful case study in how fast this changes. "Custody" and "access" gave way to "residence orders" and "contact orders" under the Children Act 1989. Those were retired in turn in 2014, when the Children and Families Act introduced a single "child arrangements order" covering both who a child lives with and who they spend time with, a deliberate move away from labels that read as one parent winning and the other losing.

A country can revise its own vocabulary within a single generation for reasons that have little to do with how families actually live, and everything to do with how the previous words were being used in court and at the kitchen table.

What the label doesn't predict

Comparative research suggests the legal label is a weak predictor of what actually happens in a given country. A 2023 study in Demographic Research, drawing on EU-wide survey data, found that Sweden had the highest rate of genuinely equal joint physical custody among the European countries it surveyed, at 42.5 percent of children with separated parents, ahead of Finland (23.8 percent) and Belgium (19.6 percent), even though Belgium and Spain are among the countries where joint physical custody has been the law's presumptive starting point for over a decade. Having the arrangement written into statute does not automatically make it common in practice.

For families actually living the arrangement, the practical work is the same regardless of what a jurisdiction calls it: a schedule both parents can see, a shared record of decisions, a way to split costs without re-litigating "fair" every time. Coordination apps built for shared care, Lina among them, are built around that practical layer rather than any one country's legal vocabulary, which is one reason the same kind of tool tends to work equally well for a family under a delt bosted arrangement in Norway and one under a "primary residential parent" designation in Texas.