The Backstreet Boys member is being sued by an alleged victim of the brawl -- Skylar Carden, an employee of the Hog's Breath Saloon -- who has accused Carter of "striking and choking" him.
A rep for the singer had no comment about the suit.
Carter was arrested on Jan. 13 for a misdemeanor count of battery in connection with the incident. He has pleaded not guilty to the charge.
"I am human and at times it can be a real struggle to balance a healthy lifestyle. I'm not perfect and for that I am sorry," the 35-year-old tweeted on Jan. 23. "When we fall we have to get up and keep on walking. I hope you stay by my side and continue to walk with me."
Carden is represented in the suit by Mark G. DiCowden, who previously made national headlines for engaging in a heated deposition withJustin Bieber
in 2014. At the time, DiCowden was representing a Miami paparazzo who alleged that he was assaulted by Bieber's bodyguard after taking photos of the singer. The civil suit was settled out of court last year.
"Nick Carter has shown the world that he is nothing more than a backstreet thug," the lawyer said in a statement on Tuesday. "Even though Nick Carter is a celebrity, he is no different from anyone else when it comes to respecting the rights of others. Mr. Carden was just doing his job to maintain order and didn’t deserve to be attacked - getting beaten up by patrons is not part of his job description. Carter’s backhanded apology in the form of a tweet was a crude attempt to control public relations and did nothing to address his remorse for the harm he caused Carden. No amount of fame or fortune justifies Carter’s shameful and outrageous conduct. To send him that message and deter his misbehavior in the future, we will seek punitive damages against him as allowed by Florida law."
Among those coming to Carter's defense is his Backstreet Boys bandmate, AJ McLean.
"He's just trying to pick up the pieces. We're all human, we all make mistakes," McLean told ET at the Monday premiere of Finest Hours in Los Angeles, revealing that he had recently spoken to Carter via text message. "It's a learning experience for him. I know he's probably going through a lot. He's about to become a brand new father, so it takes a toll on you."
To see the NSFW footage from Carter's arrest, watch the video below.