The law against marrying an in-law was in effect in the early colonies (now United States), too.  It was part of The Act to Prevent Incestuous Marriages, Assembly of Massachusetts, 1695, thanks to Puritan leaders of the day.  A man wasn't allowed to marry his widowed sister-in-law.  The law was eventually changed in 1785. Other colonies passed laws after 1695, to include prohibiting marriage of first cousins, too. These laws devastated some families, and some moved to colonies where these marriages were legal. Alexa --- On Mon, 6/25/12, Cate Schweitzer-Toepfer <voiceofshe@hotmail.com> wrote: ...most interesting is that the heroine was unable to marry her brother-in-law after the death of her husband who died shortly after WWI ended.  The reason being it was illegal in England at the time as the brother in law told her after she had fallen in love with him.  I suspect, though Carolyn don't shame me for publishing this without my sources in place) that this law was the result of Henry VIII's trying to get an annulment from Catherine (his brother's widow) and the Pope refusing.  So when the Church of England was politicized, marrying your brother or sister in law was prohibited under the law as incest (so Henry could marry someone else and assure his heirs would ascend the throne).