Remember back in November when JPMorgan reached the massive $13 billion settlement with the Justice Dept. over allegations tied to toxic mortgage-backed securities sold to investors before the housing market went kerflumpp? A non-profit group filed suit today against the DOJ, challenging the validity of the deal and asking for a court to review it.

The group, Better Markets, filed the complaint [PDF] in a U.S. District Court in Washington, D.C., claiming that in exchange for the $13 billion, the DOJ gave Chase “complete civil immunity from DOJ for years of pervasive, egregious, and knowing alleged fraud and other illegal conduct related to the worst financial crash in the U.S. since 1929.”

In spite of the fact that this was the largest settlement ever reached by the government in a suit involving a single bank, Better Markets says nothing about the process was transparent.

“[T]his contract was the product of negotiations conducted entirely in secret behind closed doors, in significant part by the Attorney General personally, who directly negotiated with the CEO of JP Morgan Chase, the bank’s ‘chief negotiator,'” reads the complaint. “No one other than those involved in those secret negotiations has any idea what JPMorgan Chase really did or got for its $13 billion because there was no judicial review.”

Better Markets maintains that because of the lack of disclosure about the settlements and the negotiation process “no one has any ability to determine if the $13 Billion Agreement is fair, adequate, reasonable, and in the public interest or if it is a sweetheart deal” for Chase.

Among the questions raised by the complaint: How much did Chase’s victims ultimately lose through these alleged frauds? Perhaps more importantly, how much did Chase profit?

Alleging, among other claims, that the administration violated the Financial Institutions Reform, Recovery, and Enforcement Act of 1989 by including a $2 billion payment to the DOJ without a court’s approval, the complaint asks that the deal be declared unlawful and that the court issue an injunction to prevent the DOJ from enforcing the agreement until it has been reviewed and approved by a court.