Why is there in in -in-law instead of by or something similar? Simon Jester, in his answer to this question, quotes the Oxford English Dictionary which says that it originally applied to step-relatives rather than those now considered in-laws, but I still don't know why we use son-in-law instead of son-by-law.

closed as not constructive by FumbleFingers, user2683, simchona, aedia λ, MrHen Nov 4 '11 at 13:33

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. If this question can be reworded to fit the rules in the help center, please edit the question.

  • I know it's similar to english.stackexchange.com/questions/29695/…, but I think it's different because that question asks where the phrase comes from, and I'm asking what it means. – zpletan Nov 1 '11 at 1:58
  • 1
    We commonly use both prepositions "in" and "by" with "law". Come to that, we also have set phrases like Attorney at law. I don't think it's meaningful to ask why we happen to have settled on "in" for the "related by marriage" constructions. We have to use one or the other preposition, but it could just as well have been "by" or "at". – FumbleFingers Nov 1 '11 at 4:10
  • @FumbleFingers And given that -in-law is from c.1300 we may never know. Incidentally, bylaw, local ordinance, is late 13c. – Hugo Nov 1 '11 at 12:03
  • @Hugo: and byelaw, I suppose. Which is how I'd normally spell it, but maybe there's a UK/US difference there. – FumbleFingers Nov 1 '11 at 14:10
  • @FumbleFingers I'm from the UK and would normally spell it byelaw as well, but was etymologically distracted. This -by is like that in Grimsby and Forsby. And I suppose also the word by. – Hugo Nov 1 '11 at 14:24

In law is a common enough collocation. The OED records 898 examples. Its use in describing relatives is merely a particular case.

  • I don't subscribe to the OED, and don't really want to just to know the answer. Could you please post some examples of its use that do not describe relatives? – zpletan Nov 2 '11 at 19:43
  • Here are five selected at random: ‘Co-executors . . . are regarded in law as an individual person’; ‘This enclose, when justifiable, is called in law approving’; ‘which sufficient estate is in law called assets’; ‘What do you mean in law by exposing his person?’; ‘The goods were in a vendue store, a common market, a public place known and established in law.’ – Barrie England Nov 2 '11 at 20:12
  • The Corpus of Contemporary American English has 1507 entries for ‘in law’. You can see them all here: corpus.byu.edu/coca. – Barrie England Nov 2 '11 at 20:22
  • The Corpus of Contemporary American English also has 2332 entries for ‘by law’. – Hugo Nov 3 '11 at 10:13
  • I'm not surprised, but the two will be used to mean different things, or at the very least be used in different contexts. – Barrie England Nov 3 '11 at 10:29

Not the answer you're looking for? Browse other questions tagged or ask your own question.