Not always an ass ....

the law, or at least the use of its principles, can be useful to women.

I enjoyed the tale from the Times Literary Supplement of July 30, page 11, in a book review of The English and the Normans, by H.M. Thomas:

When Ranulf Flambard, Bishop of Durham, attempted to ravish Christina of Markyate, the niece of his former English mistress Alveva, she escaped by swearing she was only getting out of bed to lock the chamber door, but omitting to specify that she would lock it from the outside. The legal scrupulosity with which the Normans pursued wickedness could be turned against them.