But Duval ruled in March that the shipping channel -- nicknamed MRGO -- was a navigation canal rather than a flood-control project, and so outside the protection of the Flood Control Act.
Last week, after a 19-day trial, he found that the Corps had not acted with due care when it botched operation and maintenance of MRGO, and it wasn't making a judgment call when it ignored the safety of New Orleans residents and failed to tell Congress about the channel's environmental and safety problems.
When MRGO was completed in 1968, it cut narrowly through 76 miles of swamps and cypress forest to ease shipping between the Gulf of Mexico and New Orleans. But over the next several decades, erosion more than doubled the channel's width.
The Corps argued that much of the erosion resulted from natural forces and, in any case, was not responsible for the destructive force of Katrina, a storm of such magnitude that it would have inundated the New Orleans area with floodwaters no matter what.
But Duval disagreed sharply, ruling that the Corps' efforts to maintain and operate MRGO made things worse.
The Corps knew that the channel "would not be a static, unchanging waterway," he said, but nonetheless failed to strengthen MRGO's banks with piles of rock, dredged its depths to the extent that loose soil slid from its shores and dumped dredged muck on delicate wetlands that died and ceased to act as a barrier from salty Gulf waters.
The "Corps clearly took the position that its primary mission was to keep the shipping channel open to deep draft traffic regardless of the consequences," the judge wrote.
The consequences, according to Duval, were devastating: When Katrina hit on the morning of Aug. 29, 2005, MRGO's yawning width and the absence of protective wetlands strengthened the hurricane's winds and the surge of water from the Gulf. The levees along the channel crumbled in at least two spots and were too low to block the towering waves that rushed unobstructed towards New Orleans. Water poured from MRGO into the Lower Ninth Ward and St. Bernard Parish just southeast of New Orleans and over the levees protecting East New Orleans.
"It is the court's opinion," said Duval, "that the negligence of the Corps, in this instance by failing to maintain [MRGO] properly, was not policy, but insouciance, myopia and shortsightedness."
That negligence, the judge continued, was directly responsible for the damages suffered by five of the six area residents who filed the lawsuit. He awarded $100,000 to Lower Ninth Ward residents Lucille and Anthony Franz for the loss of their home's contents.
He also awarded $317,000 to Tanya Smith and $134.665 to Kent Lattimore for damage to their homes and furnishings and for living expenses and inconvenience, and $168,033.25 to Lattimore & Associates for damage to its office and contents, all located in St. Bernard Parish.
Duval denied the claim of a sixth plaintiff, Norman Robinson, because the flooding that damaged his home was caused by the absence of a higher barrier along MRGO's border with East New Orleans. The channel's original design did not include such a barrier, and so its absence was not the result of any negligence by the Corps in maintaining and operating MRGO, the judge ruled.