A county official in Virginia banned a local on her Facebook page after the latter accused the official of nepotism.
The ban was ruled unconstitutional on the basis of the First Amendment:
Phyllis Randall, chair of the Loudon County, Virginia, Board of Supervisors, banned Brian Davison from her Facebook page for just 12 hours. But according to a federal judge in Alexandria, that brief banishment in February 2016 was enough to violate Davison’s First Amendment rights…
… [U.S. District Judge James] Cacheris rejected Randall’s contention that her Facebook page “is merely a personal website that she may do with as she pleases.” He notes that she and her chief of staff created it shortly before she took office, that it it lists her official position and contact information, and that she uses it primarily for official purposes such as describing the supervisors’ work, implementing their policies, documenting her appearances as a representative of the county government, and communicating with her constituents.
Read more about it on Reason.