Better Markets Inc., a nonprofit led by a former partner at Skadden, Arps, Slate, Meagher & Flom, filed an unusual lawsuit Monday challenging the legality of the U.S. Department of Justice’s $13 billion mortgage settlement with J.P. Morgan Chase & Co.

“There was no judicial review or proceeding at all regarding this historic and unprecedented settlement,” Better Markets CEO Dennis Kelleher wrote in a complaint filed on Monday in U.S. district court in Washington. “The $13 billion agreement is a mere contract whereby JP Morgan agreed to pay $13 billion in exchange for complete civil immunity from DOJ for years of pervasive, egregious, and knowing alleged fraud.”