New Orleans ? During an appendectomy in 1996, surgeons discovered that Vietnam veteran Joseph Isaacson had a form of cancer associated with exposure to the defoliant Agent Orange.

But when he tried to claim payment from a settlement fund set up by Agent Orange manufacturers, he was told he was too late and, besides, the $180 million kitty had been exhausted.

On Wednesday, the U.S. Supreme Court will hear arguments on whether Isaacson, a vice principal at a middle school in Irvington, N.J., and Daniel Stephenson, a retired helicopter pilot living in Florida, can sue the chemical companies that made Agent Orange.

“We want to see if we can reopen the case for all Agent Orange veterans who came down ill,” Isaacson said. “This is what this case is about.”

The chemical companies argue that a class-action settlement has ended their liability, and a corporate advocacy group says the case could threaten the finality of all class-action judgments.

A federal judge agreed, ruling that the men’s damage claims had been pre-empted by a 1984 class-action settlement agreed to by Dow Chemical Co., Monsanto and other companies that supplied Agent Orange to the military. The chemical was used in Vietnam to strip away the dense jungle foliage that provided cover for enemy forces.

The 2nd U.S. Circuit Court of Appeal reversed that ruling, setting up the Supreme Court hearing.

In 1984, neither Isaacson nor Stephenson was ill and could not claim to have been injured by Agent Orange.

“We weren’t aware of the suit,” Isaacson said. “We hadn’t come down ill and we would have had no interest in the suit.”

An attorney representing Stephenson, Stephen Murray Jr., said the Supreme Court had held in previous cases that class-action settlements — designed to handle huge numbers of similar damage claims — do not preclude people from claiming damages for injuries that surface later.