Questions on whether or not sperm or egg donors could be liable to pay child support have been raised since a US judge ruled that a man must pay child support for the child of a lesbian couple who he donated sperm to, after they split up.

A Kansas judge recently ordered William Marotta, a sperm donor to a lesbian couple, to pay child support after they split up, raising questions of how the law protects sperm donors, reports Yahoo.

Mr Marotta and the couple he donated to did not use official channels, and instead met up using the website Craigslist, and they wrote up their own agreement.

Because the US state of Kansas did not have a legal way for same-sex couples to marry, when the couple split up, the Kansas Department of Children and Families sought out the biological father of the child for child support.

The department said that laws protecting sperm donors only if they follow state laws, such as using a registered doctor, and filling in the appropriate forms, which would normally exempt sperm donors from owing child support.

Laws in the state of New Jersey are similar to those in Kansas, said Bari Weinberger, a leading family law attorney, and managing partner of Weinberger Law Group.

He said that a judge could rule that any agreement made between a couple and a donor is null and void, unless they use official channels, and follow the appropriate laws.

He said: “In Kansas, as in New Jersey, sperm donation laws state that when artificial insemination takes place under the supervision of a licensed physician with semen donated from a man who is not the woman’s husband, the husband is treated as the child’s natural father under the law.

“The husband (and wife) both must consent to the procedure in writing which is then validated by the administering physician,” Weinberger explained, referring New Jersey Law.

Mr Weinberger went on to say that he beleived the case of Mr Marotta, could possibly highlight a grey area in the law, which needed to be updated.

He said: “New Jersey [sperm donor and artificial insemination] statute discusses husband and wife specifically, and is outdated. New Jersey now recognizes civil unions and many states are now recognizing same sex marriages, so perhaps this issue is ripe for litigation or legislative updating,”

Some states, including New Jersey, recognised “psychological parents”, such as the step-parent of a child, who could be liable to pay child support as the result of a couple breaking up.

Mr Weinberger said that these definitions, and the liability of people in relationships with children in their care to pay child support, needed to be updated and clearly laid out.