The council of the Writers Guild of America, East recently voted to bring Rivers before a three-person trial board to answer allegations that she violated the union's rules by writing and performing show-runner duties for the E! Network show Fashion Police during a strike.
Writers Guild members have been on strike against the producers of Fashion Police since April 17 in an effort to secure union wages and benefits.
Rivers is a host of the show and is member of the East Coast guild.
"We are distressed by reports that Joan Rivers, who worked so hard to create an illustrious career, turned her back on other writers who are still building careers of their own," said Michael Winship, WGAE president. "We cannot prejudge the outcome, but we can say that it is a very serious matter when a member is accused of writing and show-running on a non-covered show, and continuing to do so after the other writers have decided to go on strike for reasonable pay and benefits."
Rivers was not immediately available for comment.
A trial board of three WGAE members will be appointed shortly. Rivers will be given the opportunity to present her case directly to the trial board, which will also hear evidence, including from the striking writers, the guild said.
Earlier this week, the Writers Guild of America, West, released a series of video testimonials from Guild members asking Rivers, a host of the show, to resolve the dispute.