I remember a church in Oklahoma being taken to court by a former member. Someone familiar with the case told me they had posted a notice of withdrawal from her in a public place (like a grocery store bulletin board or some such).
Ah! It's the Collinsville, OK, Church of Christ.
This 1984 article in "The Oklahoman" doesn't mention the public posting, so I could be wrong. I just remember being told that the church had done a lot wrong, and that it shouldn't affect churches' ability to withdraw from members. The article does say that the woman had already resigned from the church, and that they hadn't accepted her resignation.
Searching further: I still can't find anything about the public posting, so it seems that was bad information. This 1989 article in
Tulsa World says that the OK Supreme Court said she had no grievance over the church's actions while she was still a member, but that she
did have a grievance due to their actions after she had resigned.
And the whole thing is so typical!
Another article I found, an interview 20 years later with the church's lawyer, says that she was an unmarried mother of three and that the church had helped her quite a bit, but after she got on her feet she wasn't so interested in attending any more. I've seen that several times myself. But in the CoC, you don't let people go! So when she was going to get married, they met with her several times to try to talk her out of it. After she resigned they weren't willing to let go, it seems. Wow, this is all so familiar. They don't want to help people, they want to "save" them. Makes sense when you're on the inside, but from outside it's horrifying. The MDR rules ruin people's lives. Plus, churches latch on to people like that and the people latched onto are probably pretty happy at first -- until it starts to feel like a cult.
Anyway, other than public embarrassment and harassment (sending letters, elders attempting to contact you, announcing to the congregation that people should contact you, and finally that they have withdrawn from you) the church can't really do anything.
As you say, if you go through the process of doing it yourself (especially officially, in writing), then they can't legally do anything other than announce that you're no longer a member. But you know good and well they'll say something like "if you feel you still might have any influence on them, their soul's in danger, so please try to help them!"