In-law

Hi Dwayne. Have you seen my chainsaw lately?

Dear Word Detective: What is the root meaning of “in-law”? I know it means “related by marriage,” but where did its usage first begin? — Donna Carrico.

Hooray for in-laws! Gosh, what wonderful people. While you may suspect a forced smile behind that sentiment, I have nothing but warm feelings towards all my in-laws. And that has almost nothing to do with the fact that the “in-laws” who live closest to me also happen to be heavily armed and possess poor impulse control.

“In-law” is one of those odd locutions we use nearly every day without pausing to consider what it really means. If you think about it, “in-law” is really a rather chilly modifier, implying that if it were not for some arcane stricture of “the law” (what law?), you wouldn’t even consider loaning fifty bucks to that shifty fellow who married your wife’s sister. Maybe you would, maybe you wouldn’t even answer the phone, but “in-law” as a description of the relationship seems like something just shy of a restraining order. Perhaps it’s the natural mental pairing of “in-law” with “outlaw” that does it.

In any case, “in-law” is, according to the Oxford English Dictionary, “A phrase appended to names of relationship, as father, mother, brother, sister, son, etc., to indicate that the relationship is not by nature, but in the eye of the Canon Law, with reference to the degrees of affinity within which marriage is prohibited.” Anyone with in-laws knows that the relationship is not natural, but the relevant bit of that definition is the fact that it is “Canon law,” rather than civil law, that made the original rules about “in-laws.” Canon law is the internal law of churches, in the case of “in-law” in English, specifically the Church of England.

While Canon law today deals primarily with the internal workings of the church (ordination of clergy, etc.), in past centuries Canon law had the force of civil law, and in ruling on the legality of marriages the church considered what is called the “affinity” of the parties. Two people getting married created various degrees of “affinity” between their families, and there were specific rules about who in those families could, thereafter, marry whom. The rules varied over time, but at one time it was not legal under Canon law, for instance, for your brother to marry your wife’s sister, or your father to marry your wife’s mother (even presuming the relevant spouses were no longer around to object, of course). The suffix “in-law,” therefore, was a sort of marker declaring certain relatives by marriage to be “off limits.” Interestingly, at one time “in-law” was also used to denote the relationship we signify with “step” (“step-son,” etc.) today.

Most of these “in-law” restrictions have been abolished today, and I actually happen to know someone whose sister married his wife’s brother years ago. But none of those people speak to each other any longer, so maybe those “in-law” rules were a good idea after all.