So did this woman send a letter to the church saying she disfellowshipped the church because they were going to discipline her for being in an affair?
The story seemed to say that she had already removed herself from the church's membership before the church took action. Seems to me that would make the action of the church illegal.
What makes you think that?
If the Church has some kind of formal articles of membership, like lots of the evangelical type churches do, and if the member signed on to those articles, then she doesn't get out of them just by saying "I'm not a member anymore."
If you sign a lease on an apartment, you can't break it just by sending the landlord a letter saying "Adios." There could be a similar principal at work here. None of us know because, although the article says each member signed something, we don't what it was that was signed.
Without knowing that, we're all just guessing. But I'm guessing that if the member signed a document like some of the "covenants" I've heard about, they won't have much of a case.
I'd be real careful about comparing this to that situation up in Oklahoma a few years back involving a CofC. A CofC doesn't have any kind of membership agreement or covenant, and we generally recognize an individual's right to go join another CofC at the drop of hat. Not everybody is as slipshod as CofC's are in that department.