Tarka Cordell, 38, of London, said in court papers filed on Wednesday that 25-year-old Luke Weil struck him with a bottle, broke it over his head and then beat him with his fists at the loft apartment of artist and sculptress Hope Atherton.
Cordell was taken to a hospital and his lacerated scalp was closed with eight staples, said his lawyer, Alan Schnurman. The lawsuit seeks unspecified damages.
Weil, son of Autotote gambling equipment CEO Lorne Weil, was a subject of the documentary Born Rich, in which he bragged that he taunted poorer peers by saying, "My family could buy yours."
Weil sued director and Johnson & Johnson heir Jamie Johnson, claiming he was tricked into taking part in the film and humiliated, but the lawsuit was dismissed. Johnson was also reported to be at the party.
Weil was arraigned on Tuesday on assault and attempted assault charges related to the alleged attack on Cordell and told to return to court on February 17.
"We have confidence in the courts and we are confident that when the whole story comes out, we will prevail," said Weil's lawyer, Chuck Clayman. He refused to answer questions or comment further.