Louisiana’s Department of Insurance has joined a lawsuit filed by Mississippi against the federal government to try to block rate hikes in the National Flood Insurance Program.

Commissioner Jim Donelon said Wednesday that the department had filed an “amicus curiae, or friend of the court” brief in Mississippi’s lawsuit.

Donelon says the proposed increases under the Biggert-Waters Act could be devastating for south Louisiana homeowners. He says the changes, which require substantial increases in premiums, would disproportionately affect coastal residents.

The lawsuit asks a federal judge to find that the Federal Emergency Management Agency was obligated to deliver an affordability study to Congress by this past April, but had failed to do so. The suit asks the judge to block rate increases until FEMA has done everything the law requires.