BBC Radio 4's Law in Action was broadcast on Tuesday, 21 March, 2006 at 1600 GMT.
English Football Association rules prevent girls and boys playing together in competitive matches from the age of 12 upwards. But that is not the norm in Europe or even elsewhere in the UK.
In Scotland the age limit is 15: in Wales girls and boys can keep playing together up the age of 16, if there are no single sex teams near them: and in Northern Ireland there is no set age.
Our reporter Mayo Ogunlabi went to meet a girl who, with the help of Culture Secretary Tessa Jowell, is challenging the rules. She is 10-year-old Minnie Cruttwell, described by her father as a cross between John Terry and Roy Keane.
And we hear from sports barrister Simon Pentol about whether a challenge through the courts would be likely to succeed.