The Supreme Court has said the Government's £18,600 income threshold that bars UK workers' foreign spouses is lawful.
The policy, brought in when Theresa May was Home Secretary, has been blamed for keeping families apart because British citizens living in the UK do not earn enough money to bring their partners to the country. It holds even if their partner's earnings would tip them over the limit.
The court's decision means thousands of couples may remain apart. But it also determined the rules and instructions behind the income threshold are not lawful when it comes to the welfare of children.
Britons have previously told The Independent they have had to move abroad to be with their families because of the policy, and the Supreme Court judges admitted it has caused—and will continue to cause—"significant hardship to many thousands of couples".
The judges said that while a minimum income requirement is "acceptable in principle" the way it has been implemented unlawfully fails to take "proper account" of the Home Secretary's duty to safeguard children. The rules must be amended to take this into account, and also to allow "alternative sources of funding" to be considered.
They added: "The fact that the minimum income requirement may cause hardship to many does not render it unlawful. It has the legitimate aim of ensuring that the couple do not have recourse to welfare benefits and have sufficient resources to play a full part in British life.
"The income threshold chosen was rationally connected to this aim and the acceptability in principle of an minimum income requirement has been confirmed by the ECtHR."
In their full judgement, the justices recognised the income limit "has caused, and will continue to cause, significant hardship to many thousands of couples who have good reasons for wanting to make their lives together in this country, and to their children".