President of Family Division Resets the Framework for Expert Evidence

In Re Y (Experts and Alienating Behaviour: The Modern Approach) [2026] EWFC 38, the President of the Family Division Sir Andrew McFarlane revisited a 2019 case in which a mother had been found to have alienated her children from their father, with the children subsequently removed from her care. The President found that the approach taken in the original proceedings was ‘fundamentally flawed’ and that every agency involved — including the expert, the local authority and the judge — had been at fault. Most critically, the trial judge had accepted the expert psychologist’s opinion that parental alienation had occurred without first establishing the factual matrix required by established case law, and in particular without determining whether domestic abuse had taken place. The President confirmed that ‘parental alienation’ is not a clinical diagnosis that a psychologist can or should offer to the court; it is a question of fact for the court alone, to be determined on evidence of actual parental behaviour once the relevant facts have been found.

For practitioners instructing psychological or psychiatric experts in proceedings involving allegations of alienating behaviour, Re Y provides clear and binding guidance on how expert instructions must be scoped and sequenced. Letters of instruction must not invite an expert to opine on whether parental alienation has occurred — that determination is reserved to the court. Experts should instead be asked to address relevant psychological and psychiatric factors within the factual framework the court has already established, including the impact of any found or alleged domestic abuse on the child and on each parent’s functioning. The judgment also reiterates that only HCPC-registered or BPS-chartered psychologists should be instructed absent cogent reasons to the contrary, reinforcing the regulatory direction of travel confirmed by the new FPR 25.5A. Practitioners should review all outstanding letters of instruction in alienation-adjacent proceedings to ensure compliance with the approach set out in Re Y before those matters come before the court.

Source: The Bureau of Investigative Journalism, 27 February 2026