Best known for his work on TV's "Entourage," Piven dropped out of the revival of David Mamet's "Speed-the-Plow" in December, claiming doctors advised him to take it easy after high levels of mercury were found in his bloodstream.
However, the producers of the play have filed a complaint with Actors' Equity, alleging Piven's abrupt departure left the production in the lurch.
Sources told the New York Post Piven is to attend and bring medical records to Thursday's hearing on the matter. He is also expected to explain his side of the story to the grievance committee, which will be comprised of five actors and five producers.
Insiders told the newspaper Piven attempted to get other actors to replace him, and complained about being bored before he quit the show due to the alleged illness.
The Post said producers kept a record of where Piven's car and driver took him after performances, however, and paperwork indicates he was out partying on many nights instead of being home sick like he said he was.
If the grievance committee rules against Piven, the actor could face paying a financial settlement to the producers, possible expulsion from the union and/or a civil lawsuit.
The Post said Piven's publicist wasn't available for comment before press time.