Duval has also dismissed a parallel lawsuit against a contractor. It claimed excavation work weakened flood walls in New Orleans' Industrial Canal. Duval entered the orders to dismiss the cases on Dec. 20.
More than 500,000 residents, businesses and governments filed claims against the Corps. People in southern Louisiana have long taken for granted that the flooding in the wake of the 2005 storm was a man-made disaster — one caused specifically by the corps — and they have wanted the agency to pay up for lost homes and property.
The corps claimed immunity from suits related to decisions on flood-control projects, including most levees, based on a 1928 federal law. But lawyers tried to get around that by claiming the agency had been negligent in maintaining navigation channels, including the Mississippi River Gulf Outlet.
That channel, dug in the 1960s and closed after the hurricane, funneled Katrina's storm surge into parts of the city. Overall, thousands of homes were destroyed, about 1,400 people died in the flood and much of the city was left under water.
Duval had ruled in 2009 that the corps was liable for the flooding of New Orleans' Lower 9th Ward neighborhood and St. Bernard Parish because the agency failed to properly maintain the channel, allowing protective marshland to wash away.
The 5th Circuit Court of Appeals initially agreed with that decision in March 2012. But in September, a three-judge panel reversed its earlier opinion, saying the new ruling "completely insulates the government from liability."
The ruling could make it extremely difficult to force the government to pay damages for future mishaps.
Under federal law, the government cannot be sued over actions based "on considerations of public policy," the appeals panel wrote. The corps' decisions regarding the shipping channel fall under that protection, the judges wrote.
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