She's running 'marital coercion', according to the link. Blimey, her QC must have got a junior [counsel] who's a) not a criminal practitioner (a crime boy wouldn't think of it or find it in the law books) b) believes that antiquated law, even though revised, is going to go down well with a judge in a criminal court or the jury (who will be disinclined to accept the idea that a wife, let alone this wife, is so dominated by her husband who was present that she loses free will). It's virtually the same as duress which is very difficult to establish; the defendant has to prove it on the balance of probabilities and it has to be such action or words as to cause someone to do the crime because they are in such fear that they can do no else. If the man was that threatening or violent in nature, and over such a matter, it's a wonder she is still with him. But if she's running it, that doesn't bode well for his case since it amounts to saying that he knew, or believed, he was guilty.
As to politicians being treated more severely, well it's a bit odd that anyone feels it necessary to resign when they either have not been charged or have not been convicted