Where did the term "in-law" originate?

Question

Is it just saying that the mother, brother, etc is your relative in the eyes of the law? Or is there another reason? Just curious where this originated. Thanks!

Answer 1

The previous answerer says it pretty well.  (Why call yourself "Bonehead"?!)  However, the realtionship doesn't actually impart much legal status, at least in terms of inheritance.  If someone dies intestate and the biological child is deceased but left a widow or widower and children, the children inherit, but the son- or daughter-in-law doesn't.  Or if someone wills property to a son or daughter and that person's spouse, the biological child pays a lower rate of inheritance tax than does the in-law.

However, according to the Oxford English Dictionary, the term, first used in English in the 14th century, refers to CANON law in reference to whom one was and was not permitted to marry.  In that context, a parent-, child-, or sibling-in-law was just as off-limits matrimonially as the biological counterpart.  Thus Hamlet refers to his mother's marriage to his dead father's brother as incestuous, and Henry VIII  went through some canonical red tape to establish his right to marry Catherine of Aragon--and then through more when he changed his mind twenty-odd years later.

The "in-law" construction seems to be peculiar to English, anyway.  In French, one's parents-in-law are "beau pere" and "belle mere," which are also the terms for step-parents.  (Of course, you may remember that in David Copperfield, Mr. Murdstone, whom we would think of as David's step-father, is referred to at least once as his "father-in'law.")  Spanish has special names for in-law relatives, as do German and  Latin.

This tidbit may also be of interest:  some people today still call their parents-in-law (for example) "Mother and Father Smith" or "Mom and Dad Smith."  At one time it was also the practice to call one's daughter's husband "Son Jones."

Is that more than enough?

Answer 2

I guess you could say "by law" too but it's simply identifying the relationship as being made through the legal joining of a couple in marriage

Answer 3

It describes their relationship to you as being of legal origin (a marriage) , not blood.