Leeds Teaching NHS Hospital Trust v A [2003] 1 FLR 1091 High Court Facts Mr and Mrs A sought reproductive treatment, with Mr A's sperm mixed with Mrs A's eggs. Mrs A gave birth to the twins and was their biological father. However, owing to a mistake, Mr B's sperm were wrongly mixed with Mrs A's egg, meaning Mr B was their biological father. None of the parties involved consented to this happening. Who was the legal father?
Held Butler Sloss P

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[s.35 Woman married at time of treatment o (1)If---
? (a)at the time of the placing in her of the embryo or of the sperm and eggs or of her artificial insemination, W was a party to a marriage, and
? (b)the creation of the embryo carried by her was not brought about with the sperm of the other party to the marriage,

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then, subject to section 38(2) to (4), the other party to the marriage is to be treated as the father of the child unless it is shown that he did not consent to the placing in her of the embryo or the sperm and eggs or to her artificial insemination]

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41Persons not to be treated as father o (1)Where the sperm of a man who had given such consent as is required by paragraph 5 of Schedule 3 to the 1990 Act (consent to use of gametes for purposes of treatment services or non-medical fertility services)
? was used for a purpose for which such consent was required, he is not to be treated as the father of the child.]

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Assisted reproduction and fatherhood when parties married o Looking superficially at [s.35(1)(b)] , it might appear that Mr A could be the legal father of the twins,
? since, at the time of the placing in Mrs A of the embryo, Mrs A was a party to the marriage with Mr A and the creation of the embryo carried by her was not brought about with the sperm of Mr A. o But this is subject to two provisos.
? The first is contained in [section 38(2) to (4)] and provides for the common law presumption of legitimacy of a child born to a mother during her marriage.

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In the present case, that presumption is displaced by the DNA tests which established that Mr B is the biological father of the twins
? The second proviso, contained in [s.41(1), is the requirement of the husband's consent.

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It is obvious that [s.35] is not relevant if the sperm given by Mr A was used since he is then the biological father and the twins are the legitimate children of Mr and Mrs A.

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