If two people, male and female marry, and then the sibilings marry, is anybody
in a state of incest?  Brother 1 and Sister 2 marry...Brother 2 and Sister 1
marry...is this legal or incest?

Hi passerine-ga,

Laws differ from place to place. I'm assuming you're in the USA. If
you're from somewhere else, please use the "Request Clarification"
facility to let me know where.

According to the following website, it's legal in the USA:

  "The Anglican regulations ... once included a ban on marriage
   between a brother-in-law and sister-in-law, even after the
   death a connecting spouse. However, no states currently include
   this prohibition, nor does the Church of England."

   "State Variations in American Marriage Prohibitions"
   http://www.umanitoba.ca/anthropology/tutor/marriage/usa-ncst.html

The registrar of marriages (or equivalent in your state) would be able
to confirm this authoritatively.

Regards,
eiffel-ga


Google search strategy:

incest sister-in-law OR brother-in-law
://www.google.com/search?q=incest+sister-in-law+OR+brother-in-law

I can confirm that the situation is the same in the UK as they do not
have a prohibited degree of relationship.

I can confirm that the same situation is true in Israel, since I have
relatives who did that.

Judaism is not only okay with marriage between in-laws; the religion
used to encourage it. Let me explain: if  woman got widowed, her
brother-in-law was encouraged to marry her so that she could live in
dignity and out of poverty.

No blood relation = no incest.