A legal clerk who refuses to pay child support to his ex-wife because their three teenage sons spend half their time with him has been jailed.
Michael Cox, 43, a prominent member of Fathers for Justice, has failed to pay maintenance for 12 years because he claims the system is "oppressive, unjust and discriminatory" towards men.
One of his 13-year-old twin sons burst into Southampton magistrates' court to plead for his father not to be jailed.
Mr Cox's ex-wife, Lesley Peach, also begged the court not to lock him away because in his absence she would have to give up her job in a taxi office and look after her children full time.
But a 42-day suspended prison sentence was activated because he refuses to pay a ?45,000 backlog. The magistrates' chairman Christine Smith said: "We are satisfied that the interest of the children have been considered."
Mr Cox, who has two more children with his second wife Beth, is paid nothing for the time he looks after his three teenage boys, but the Child Support Agency demands he pay their mother ?365 a month for the time they are with her. He said: "It is outrageous that people are released early from prison for serious crimes and yet I'm being locked up, as a caring father."
The court heard Mr Cox, from Hythe in Hampshire, split from his first wife in 1994. Apart from the twins they have another boy of 16.
Since his 40-year-old ex-wife, who has remarried, receives child tax credits she is considered to be the official parent, or "registered parent with care". This status means she also is entitled to child maintenance.
In cases where one parent is absent this arrangement is useful because it helps work out who should be paying.
But Mr Cox, a trained lawyer who advises Fathers for Justice on legal matters, claims it is unfair in his case because it does not take into account the fact he looks after his children half the time.
Mr Cox, who represented himself, told Southampton magistrates: 'I have been referred to as an absent father, but that's not what I am.
"I'm a father who well knows the obligation to his children and I discharge that obligation. I feed all of my children, I clothe them, I house them - that's what I spend my money on. The CSA gives me no assistance for that and requires me to spend the money twice. I say that makes it oppressive, unjust and discriminatory in its action.
"In this case you have two established families living in equilibrium. My ex-wife lives a mile away from me and the children pass easily between the two households.
"They spend half of the time with me and half of the time with their mother. My ex-wife is not a little old lady living in a shoe, reaching in the back of a cupboard for the last tin of beans.
"This is not about the law. According to the law I'm dead in the water, I'm bang to rights."
After Mr Cox was led away in handcuffs his 32-year-old second wife, a junior school teacher, said: "It just defies all logic and sense. The sentence has impoverished two families, on both sides - both him and his exwife."
Mrs Peach said: "The boys are in tears and very upset about this. The CSA are not looking out for their interests at all and are just damaging the children.
"I am happy with the arrangement between my ex husband and myself and at the moment don't want any money from him.
"We both help each other out and compromise: right now he is having the children an extra night a week so I can work. It's fine.
"Now he's been jailed I may have to stop working and go on to benefits because I can't work and look after the kids at the same time.
The hearing was attended by a dozen Fathers for Justice members.
The group's founder Matt O'Connor said: "It is utterly disgusting to jail a very courageous and brave individual and a loving father who cares for his children."
The CSA, which is currently being reformed, said: "We cannot comment on individual cases."