Former Vice President Al Gore is suing Al Jazeera America, saying the news network is withholding tens of millions of dollars that it owes for buying Current TV from him and other shareholders for $500 million last year.

Gore’s attorney, Boies, Schiller & Flexner chairman David Boies, said in a statement that Al Jazeera America “wants to give itself a discount on the purchase price that was agreed to nearly two years ago.” He said the suit was filed in Delaware Court of Chancery on Friday.