The defence of marital coercion used by Anne Darwin is extremely rare with only five reported cases in the last 75 years.

One involved a drink-driving case against Ashley Fitton, 37, of Unsworth, Bury, who was acquitted at Manchester City magistrates’ court after she successfully raised the defence under section 47 of the Criminal Justice Act 1925.

The legislation provides that a wife has a defence to any charge other than murder or treason if she committed it “in the presence of, and under the coercion of, her husband”.

Mrs Flitton was three times over the limit when caught driving her family in a Jaguar but claimed that at the end of the evening out she had been forced to take the wheel by her husband.

Professor Gary Slapper, director of law at the Open University, said: “It used to be a legal presumption that an offence committed by a wife in the presence of her husband was committed under his coercion.

“That looked a bit anachronistic by 1925 when the rule was abolished. From then, the defence of marital coercion was available, but had to be proved on the balance of probabilities - meaning it needs to be more likely to be true than not.”

But in 1977 the Law Commission, the Government’s law reform body, recommended the abolition of the defence, saying it was “not appropriate to modern conditions”.

Its draft criminal law bill would have removed this separate and dedicated defence of cooercion for wives - but it has never been enacted.

The Commission also then said that there were “uncertainties” surrounding the defence and noted the strictness of the requirement, since relaxed a little, that the husband has to be physically present when the wife commits the offence.

Other criticisms were that it was irrational to provide a special defence to wives that was not available to other women placed in an equally vulnerable position.

Professor Slapper added: “It is unsustainable for the law to set apart wives and afford them a defence which is not available to wives or other cohabitants.

“Teenage children who commit crimes in the thrall of tyrannical parents are given no special defence; nor are life partners, whether heterosexual, gay or lesbain, who are dominated by a menacing other half.”

And, he added, marital coercion clearly works both ways. “There are many documented cases of husbands being bullied and coerced by violent wives.”

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