Judgment has now been handed down in Re J, M-S-K-B & P [2026] EWCA Civ 344, a case in which 16 members of Chambers and 2 door tenants appeared in the Court of Appeal over the course of 3 days.

The issue central to all three of the conjoined cases is the attribution of parental responsibility by an unmarried father by way of being named on the child’s birth certificate. Specifically, whether parental responsibility was ever obtained by a man named on the child’s birth certificate as the father, in circumstances where it subsequently transpires that he is not the biological father of the child (or there cannot be certainty as to whether they are the biological father of the child).

In Re J, there had been a genuinely held belief by both parties at the time of registration that the individual named as ‘father’ on the birth certificate was also the biological father of the child. In Re M the parties had always known that the individual named as ‘father’ on the birth certificate was not the biological father. In Re P, it was not possible to determine which of two putative fathers was the biological father and therefore should be named on the birth certificate, owing to them being identical twins.

In summary, the Court of Appeal has determined that:

• Parental responsibility was never acquired by the individuals wrongly named on the birth certificate as the father regardless of belief at the time of registration;
• Parental responsibility by way of birth certificate only ‘attaches’ to the individual named if they are the biological father;
• The definition of the word ‘father’ when used within the CA 1989 is the common law definition and is therefore limited to a child’s biological father.