I understand "common law" in Texas, I did it for 7 years before actually marrying legally - and I even got hubby's medical benefits because of it.
This will be something left to the courts and will not be as simple to prove as it seems....BOTH PARTIES in the marriage have to represent themselves publicly AS MARRIED - and I doubt a single FLDS-er will swear that the couple did so in their presence. Plus the spiritual wives go OUTSIDE the FLDS and represent themselves to the STATE (to get WIC and Food Stamps) as UNMARRIED single mothers - no fathers/husbands anywhere. I am not even sure, based on the remoteness of the ranch and it's forced seclusion that the state can even prove the couples co-habitated EVER. I mean these women and children live in HUGE DORMS with communal sleeping rooms for the kids and a big industrial shared kitchen area - not even sure where the husband would call his "room"? Perhaps ONLY with wife #1 (legal wife) and the other women are just "room-mates of theirs? And they get their mail at separate PO boxes within the ranch - so each woman must have a separate LEGAL address on record with the state, sans husband or father.
Common Law marriage usually involves - JOINTLY OWNED PROPERTY - which I can assure you, the FLDS doesn't "do" - heck, they don't own ANYTHING - it's either owned by the husband's business or the YFZ version of the UEP. There is no real PERSONAL PROPERTY - it isn't "done" that way in the FLDS (more control over even the MEN that way). Nothing on the YFZ Ranch is owned by ANYONE living there (at least in the eyes of the state) - and I am betting that each business may be a CORPORATION - owned by members of the UEP - NOT and individual person. Common Law Marriage is supposed to be judged on the INTENT of the two people and is often set by HOW LONG the two have been "together" - again, not something easily proved by the authorities. These folks won't even reveal who's kids are whos - I doubt they are going to be any more honest about something that could get their husband/priest thrown in JAIL.
My Opinion