Mr. Fortner, whose county has transformed from predominantly white to decidedly mixed over the past two decades, said that the Georgia statute upon which the second charge is based, the Street Gang Terrorism and Prevention Act, was “worded very broadly to deal with any type of activity that occurs with a group that’s organized that commits a crime.”

None of the accused had been arraigned as of Monday, and it was not clear if they had lawyers representing them. By Monday afternoon, none of them had applied for representation with the county public defenders’ office. But a member of the group told a local newspaper that the black partygoers started the confrontation.

Several criminal lawyers and legal scholars said Monday that they could not recall other instances in which a state anti-gang statute had been used to prosecute a Confederate heritage group in the Deep South. The first version of Georgia’s anti-gang law was passed in 1992 at the behest of Atlanta’s police chief at the time, Eldrin Bell.

The state’s General Assembly, in the law’s statement of intent, noted that citizens retained their rights to freedom of expression and association. But it also declared that Georgia was in a “state of crisis which has been caused by violent criminal street gangs whose members threaten, terrorize and commit a multitude of crimes against the peaceful citizens of their neighborhoods.”

Pickup trucks flying Confederate-themed flags have become a regular sight in many parts of the South since June, when a white gunman, apparently influenced by racist doctrine, massacred nine black worshipers at a Charleston, S.C., church. A subsequent effort by some elected officials in the region to remove Confederate symbols from public spaces has provoked a strong negative reaction from some white Southerners, who argue that the symbols are a part of their history and heritage.