A lesbian whose former partner bore a child through sperm donation cannot be ordered to pay any maintenance, a High Court judge in the UK ruled yesterday.

The former couple never contracted a legal civil partnership and, as the law stands, the woman who did not have the child could not be defined as a ‘parent’.

Mr Justice Moylan said the woman, identified only as B, was a ‘social and psychological’ parent of the child born in 2000.

But he said the law differentiated between a natural parent and a legal one.

He said: ‘I have come to the clear conclusion that those against whom orders can be made… are confined to those who are a parent in the legal meaning of that word.’

The judge said B had won an order in the courts for shared residence with the child and had therefore acquired parental responsibility.

‘This might appear a persuasive point, save for the fact that the mere obtaining of parental responsibility is clearly not intended to make someone a legal parent when they would not otherwise be such.’

The judge added: ‘In some respects the outcome in this case may seem objectively surprising.

‘However, in my view it is for the legislature to determine who should be financially responsible for children if it is to extend beyond those who are legal parents.

‘If I were to extend the definition to include anyone who has acted as a parent, I do not see how I could properly define the limits of such an extended definition in a way which would provide sufficient legal certainty.’

The courts were not the proper forum to decide that a particular person in a given case should be treated as a parent and thereby be open to financial obligations, he added.

Mr Justice Moylan, who handed down his judgment in Leeds, said the mother of the child, identified as T, had argued through her legal team that B was a legal parent.

He said they began a relationship in 1994 and lived together until 2007.

T became pregnant using an unknown donor through an authorised clinic after they both applied for her to have the treatment.

When their relationship broke down, B issued an application for residence and contact and in January last year a district judge made a shared residence order.

The High Court judge was asked to rule on whether B is a parent under the Children Act, which determines if the court had jurisdiction to make a financial order against her.

Iain Goldrein QC, representing T, had argued at a private hearing in March that the parties agreed to participate jointly in the child’s birth and they both then took on the role of the child’s parents and still continue to do so.

Charles Hyde QC, representing B, said his client was not a parent within the law and the court had no power to make an order for maintenance.