$20 billion fortune, a Russian divorce and English family law…
What happens when a $20 billion fortune, a Russian divorce and English family law, are all in the same room? Well, you get Potanina v Potanin, which is a case much like a soap opera, legal thriller and a lesson in procedure.
Background
Natalia Potanina (“the wife”) and Vladimir Potanin (“the husband”) were married in Russia in 1983 and divorced there in 2014. Over decades, the husband amassed immense wealth, estimated around 20 billion US dollars, which are largely held through trusts and corporate structures, though he remained the beneficial owner.
After the divorce, the wife received a modest settlement under Russian law, as assets held beneficially were excluded. She relocated to England on an investor visa in 2014, became habitually resident from 2017, then sought permission under Part III to apply for further relief.
What is a Part III application?
A Part III application, under the Matrimonial and Family Proceedings Act 1984, allows individuals to seek financial relief in England and Wales following a divorce granted in another country.
If a settlement received abroad was unfair or inadequate, and there is a sufficient connection to this jurisdiction, such as residence or domicile, the English courts may step in to provide a more just financial outcome. It’s a valuable remedy for those left financially vulnerable by overseas divorce proceedings.
So, what has happened since?
An initial ex parte hearing in January 2019 granted her leave to apply under Part III. The husband applied to set aside this leave, arguing the judge had been misled and that the application lacked “substantial grounds”. Mr Justice Cohen ultimately set aside the leave in November 2019 upon reconsideration.
The Court of Appeal reversed that decision: following authority in Agbaje v Agbaje [2010] UKSC 13; [2010] 1 AC 628 and Traversa v Freddi [2011] 2 FLR 272, a setting aside should require a “knock-out blow”, a decisive reason such as clear misleading or overlooked authority; otherwise, the leave should stand until the substantive hearing.
The 2025 appeal judgment
In Potanina v Potanin (No. 2) ([2025] EWCA Civ 1136), Lord Justice Cobb and colleagues examined the appeal from Justice Cohen’s set-aside judgment, the key findings included the following:
1. Justice Cohen’s reconsideration amounted to a mini-trial, far over the intended brief filtering action for ex parte leave.
2. The “knock-out blow” threshold was not met; the husband did not present decisive reasons warranting immediate revocation of leave.
3. The correct approach mandates that, absent such a blow, leave should remain in force and the application proceeds to full hearing; anything more resembles a “split trial” better suited for substantive proceedings.
Why does this matter?
This judgment underscores that even in complex, high-wealth international divorces, legal process must remain streamlined and principled. Part III exists to address inadequate foreign divorce outcomes where strong English connections exist, but the courts must not turn leave hearings into proxy or alternative trials.
This decision reinforces consistency, efficiency, and predictable litigation pathways under Part III. It ensures that applicants with solid grounds, like the wife here, aren’t unfairly barred from seeking relief due to procedural overreaching.
This judgment reminds us, that the process matters, especially in international family law where the intersection of wealth, jurisdiction, and procedural fairness is present.
