Dominic Barbara was cited for billing errors and improper staff supervision. An appellate court found him guilty of professional misconduct. It noted he has received 20 sanctions between 1988 and 2009, including nine letters of caution.
He did not immediately return a call seeking comment.
Buttafuoco served jail time for statutory rape after his 1990s affair with "Long Island Lolita" Amy Fisher. She went to prison for shooting Buttafuoco's wife. Hahn was the secretary embroiled in a sex scandal with evangelist Jim Bakker.
Barbara also represented a man whose wife and seven other people died in a wrong-way crash.