The brief reiterated in explicit terms testimony by W. Craig Fugate, FEMA administrator, before Congress that the law only gives Congress the authority to delay or otherwise forestall the rate hikes.

Moreover, the brief says, the Mississippi Insurance Department "likewise cannot show redressability because only Congress can remedy the department's claimed harm."

The brief also says Mississippi is wrong in stating that the affordability report must be sent to Congress before the rates are implemented.

The affordability study mandated by the 2012 Biggert-Waters Act requires FEMA to have a study conducted by the National Academy of Sciences. The purpose of the study, according to the law, is aimed at identifying "methods to aid individuals to afford risk-based premiums under the National Flood Insurance Program through targeted assistance rather than generally subsidized rates, including means-tested vouchers," FEMA says in the brief.

FEMA states, though, that nothing in the provision mandating the study "requires Congress to consider the information in the report, let alone to use it to change the way premium rate increases are implemented," the brief says.

FEMA lawyers argue that even if the study were completed, the agency "would still only have the authority to implement such methods if new legislation is enacted."

The brief argues that unlike the contentions of Mississippi and other states that have filed friend of the court briefs in the suit, the 2012 law provide explicit deadlines for implementation of the rate hikes, "without regard to any other actions, including when, or whether, the study required [the affordability study] in Sec. 236 is completed."

The brief was filed just after Congress made clear it has no desire to take up the issue of delaying the rate hikes this year.