The lawsuit filed in the nation's capital challenges the department's November 2013 settlement, described as the largest settlement ever made with a single company by a factor of 300 percent. The lawsuit the deal was made "with no judicial review or approval."
The Justice Department settled a case with the bank over improprieties and potential fraud that contributed to the 2008 financial crisis, which in turn was a contributing factor to the 2007-2009 recession.
"The Wall Street bailouts were bad enough, but now taxpayers are being forced to accept a secretive backroom deal that may well have been another sweetheart deal," said the group's President and Chief Executive Officer Dennis Kelleher in a statement.
"The Justice Department cannot act as prosecutor, jury and judge and extract $13 billion in exchange for blanket civil immunity to the largest, richest, most politically-connected bank on Wall Street," Kelleher said.
"The executive branch does not have this unilateral power because it violates the constitutional requirement of checks and balances," he said.
The group said the $13 billion deal pales in comparison to the damage that was done, which comes to more than $13 trillion.
"A monetary sanction of $13 billion seems small given it contributed to such economic wreckage and given the size of JP Morgan Chase, a bank with 2.4 trillion in assets," Better Markets said.