In Louisiana, the most common way to visualize the state’s existential crisis is through the metaphor of football fields. The formulation, repeated in nearly every local newspaper article about the subject, goes like this: Each hour, Louisiana loses about a football field’s worth of land. Each day, the state loses nearly the accumulated acreage of every football stadium in the N.F.L. Were this rate of land loss applied to New York, Central Park would disappear in a month. Manhattan would vanish within a year and a half. The last of Brooklyn would dissolve four years later. New Yorkers would notice this kind of land loss. The world would notice this kind of land loss. But the hemorrhaging of Louisiana’s coastal wetlands has gone largely unremarked upon beyond state borders. This is surprising, because the wetlands, apart from their unique ecological significance and astounding beauty, buffer the impact of hurricanes that threaten not just New Orleans but also the port of South Louisiana, the nation’s largest; just under 10 percent of the country’s oil reserves; a quarter of its natural-gas supply; a fifth of its oil-refining capacity; and the gateway to its internal waterway system. The attenuation of Louisiana, like any environmental disaster carried beyond a certain point, is a national-security threat.

Where does it go, this vanishing land? It sinks into the sea. The Gulf of Mexico is encroaching northward, while the marshes are deteriorating from within, starved by a lack of river sediment and poisoned by seawater. Since 2011, the National Oceanic and Atmospheric Administration has delisted more than 30 place names from Plaquemines Parish alone. English Bay, Bay Jacquin, Cyprien Bay, Skipjack Bay and Bay Crapaud have merged like soap bubbles into a single amorphous body of water. The lowest section of the Mississippi River Delta looks like a maple leaf that has been devoured down to its veins by insects. The sea is rising along the southeast coast of Louisiana faster than it is anywhere else in the world.

The land loss is swiftly reversing the process by which the state was built. As the Mississippi shifted its course over the millenniums, spraying like a loose garden hose, it deposited sand and silt in a wide arc. This sediment first settled into marsh and later thickened into solid land. But what took 7,000 years to create has been nearly destroyed in the last 85. Dams built on the tributaries of the Mississippi, as far north as Montana, have reduced the sediment load by half. Levees penned the river in place, preventing the floods that are necessary to disperse sediment across the delta. The dredging of two major shipping routes, the Mississippi River Gulf Outlet and the Gulf Intracoastal Waterway, invited saltwater into the wetlands’ atrophied heart.

Beneath the surface, the oil and gas industry has carved more than 50,000 wells since the 1920s, creating pockets of air in the marsh that accelerate the land’s subsidence. The industry has also incised 10,000 linear miles of pipelines, which connect the wells to processing facilities; and canals, which allow ships to enter the marsh from the sea. Over time, as seawater eats away at the roots of the adjacent marsh, the canals expand. By its own estimate, the oil and gas industry concedes that it has caused 36 percent of all wetlands loss in southeastern Louisiana. (The Interior Department has placed the industry’s liability as low as 15 percent and as high as 59 percent.) A better analogy than disappearing football fields has been proposed by the historian John M. Barry, who has lived in the French Quarter on and off since 1972. Barry likens the marsh to a block of ice. The reduction of sediment in the Mississippi, the construction of levees and the oil and gas wells “created a situation akin to taking the block of ice out of the freezer, so it begins to melt.” Dredging canals and pipelines “is akin to stabbing that block of ice with an ice pick.”

The oil and gas industry has extracted about $470 billion in natural resources from the state in the last two decades, with the tacit blessing of the federal and state governments and without significant opposition from environmental groups. Oil and gas is, after all, Louisiana’s leading industry, responsible for around a billion dollars in annual tax revenue. Last year, industry executives had reason to be surprised, then, when they were asked to pay damages. The request came in the form of the most ambitious, wide-ranging environmental lawsuit in the history of the United States. And it was served by the most unlikely of antagonists, a former college-football coach, competitive weight lifter and author of dense, intellectually robust 500-page books of American history: John M. Barry.

When Hurricane Katrina made landfall in Louisiana on Aug. 29, 2005, John Barry was a year and a half into writing his sixth book, “Roger Williams and the Creation of the American Soul,” about the puritan theologian’s efforts to define the limits of political power. Barry is not a fast writer; his books take him, on average, eight years to complete. “I tend,” Barry says, “to obsess.” Earlier in his career, he spent nearly a decade as a political journalist, writing about Congress, an experience he drew upon for his first book, “The Ambition and the Power.” But after that book’s publication, he quit journalism and cocooned himself in research, reading and writing. He took on vast, complex episodes in American history that in his rendering become Jacobean dramas about tectonic struggles for power. “The Ambition and the Power” would make an appropriate subtitle for any of his books — particularly “Rising Tide,” his history of the 1927 Mississippi River flood, the most destructive in American history.

Barry’s research for “Rising Tide” had made him an amateur expert on flood prevention, and in the days after Hurricane Katrina, he received requests from editors and television-news producers for interviews. He accepted nearly every one of them and within days of the storm had become one of the city’s most visible ambassadors in the national press. “I felt I had an obligation,” Barry told me, “to convince people that the city was worth rebuilding.”

Like many others, Barry was frustrated that he couldn’t figure out why New Orleans had flooded so catastrophically. When he studied the numbers — the wind shear on Lake Pontchartrain, the storm surge, the inches of rainfall — they didn’t add up. After making calls to some of his old sources, he concluded that the levees hadn’t been overtopped, as officials from the Army Corps of Engineers assumed, but had collapsed because of design flaws. (He was among the first to draw attention to this fact in an Op-Ed article published in The New York Times that October.) Barry concluded that just as in 1927, people died because of cynical decisions made by shortsighted politicians drawing on bad science. For Barry, Hurricane Katrina was not the story of a natural disaster; it was a story of politics, science and power.

It seemed like the ideal basis for a John Barry book, but Barry decided not to write a book. Instead, on the cusp of his 60th birthday in 2006, he entered public life. He wrote editorials for The Times, The Los Angeles Times, The Washington Post and USA Today. He joined state committees charged with improving flood control. He called a friend in Congress who sat on the Appropriations Committee and met with other lawmakers and their staffs. He toured flood-management systems in the Netherlands. He began to resemble Andrew Humphreys, a conflicted hero of “Rising Tide,” who arrived in New Orleans in 1850 to study flood control: “The work obsessed him, unbalanced him, pushed him to the margin. He stopped writing . . . because it distracted him. . . . He himself talked to reporters. He basked in their attention, basked in their portrayal of him as a major figure.”

In Washington, where Barry lives for part of the year, he met with a freshman representative from the state’s First Congressional District, which includes much of southeastern Louisiana: Bobby Jindal. He begged Jindal to demand action from the White House. New Orleans couldn’t count on its mayor, or on the governor, he said; the city needed a hero on Capitol Hill. After speaking for two hours, Barry recalled, Jindal said that taking a leadership position on Hurricane Katrina “didn’t fit his timing for running for governor.” (Jindal, who declined to comment for this article, was elected governor in 2007.) “I left in total disgust,” Barry said.

Barry has a special talent for disgust. His face at rest conveys a pained forbearance. A lifetime spent studying the behavior of powerful people motivated by low ambitions has made him quick to skepticism. He is a master of winces, grimaces and exasperated smiles. His voice is gravelly and low, though indignation amplifies it fivefold. At 67, Barry is 5-foot-9 and powerfully built — he participated in national weight-lifting competitions as recently as 1998. He played football at Brown and, after dropping out of a Ph.D. history program, joined Tulane University’s football team as a receivers’ coach. In his office in downtown New Orleans, the most prominent wall decoration is a laminated Times-Picayune newspaper from 1973 that celebrates the first Tulane victory over Louisiana State in 25 years. When discussing his public battles, he often summons football metaphors. “Writing is pretty isolated,” he said. “I enjoy the action. I like to fight.”

In the miasma of incompetence after Hurricane Katrina, Barry’s intellectual gravity and combativeness elevated him rapidly in the public trust. When the Louisiana Legislature created a regional levee board, Barry was urged by several local leaders to apply for a seat. The board — the Southeast Louisiana Flood Protection Authority-East, or Slfpa-E — would be responsible for overseeing all flood-management projects in its jurisdiction, which includes nearly all of New Orleans. Because the continued existence of the city depends on its ability to manage floods, this was no small responsibility. Some of the nation’s leading experts on flood protection were appointed to the board, among them California’s flood-plain-management chief, a former president of the American Society of Civil Engineers and the marine scientist responsible for one of the first efforts, in the late ‘80s, to restore coastal Louisiana. Barry was appointed in 2007 and functioned as the board’s spokesman.

Barry was curious to see how the past would inform the decisions about the city’s future. Like many historians, he is fond of quoting George Santayana: “Those who cannot remember the past are condemned to repeat it.” But he never quotes Santayana without quoting Hegel: “The only thing we learn from history is that we learn nothing from history.” For Barry, the battle for New Orleans’s survival would be fought along the Santayana-Hegel axis.

It soon became clear to Barry that despite its grand mission, the board was, as its president, Stephen Estopinal, liked to joke, an “authority without any authority.” It could not write policy, enforce law or mandate levee construction. It could serve only as a consultant to other agencies, particularly the Army Corps of Engineers — a body not particularly known for welcoming outside help. (Those interested in a history of the corps’ stubborn, hidebound nature should read “Rising Tide.”) The corps invited the levee board to meetings, but the relationship soured when the board’s experts raised objections to the corps’ flood-protection plans. “They got tired of being criticized,” Barry said. “It was a natural human response.”

Although the board had questions about the quality of the levees being rebuilt around the city, of far greater concern was the condition of the marsh south of New Orleans. As the marsh disappeared, even weak storms would inundate the city, no matter what condition the levees were in. The board realized that it was focusing on the wrong thing: The marsh, not the levees, had to be the priority. The board soon found itself pushing most aggressively for work as many as 75 miles south of New Orleans.

The state did have a plan in place to rebuild the barrier islands and coastal wetlands. Originally published in 2007 and revised in 2012, the so-called Coastal Master Plan was endorsed by scientists, as well as the oil and gas industry. It listed 109 flood-risk-reduction and land-building projects that, if executed in the next half-century, would “create a sustainable coast”; some land loss would still occur, but not nearly as much as currently projected. The state estimated that these projects would cost $50 billion. (A Tulane University study estimated the cost at $94 billion.) The state, however, had not figured out how it was going to finance the Coastal Master Plan. The main source of funding would be the settlement from the BP Deepwater Horizon oil-spill lawsuits, which is expected to be as much as $20 billion. That would leave about $30 billion.

Barry believed that other oil and gas companies should also contribute. His argument was simple: Because the industry conceded responsibility for 36 percent of land loss, it should pay its part: $18 billion would be a start. The industry, unsurprisingly, preferred that the master plan be funded by taxpayers. “Industry recognizes its role,” Chris John, the president of the Louisiana Mid-Continent Oil and Gas Association, a lobby that represents the major energy conglomerates, wrote in an editorial published in The Times-Picayune. “However, our idea of a solution is very different than that of the Southeast Louisiana Flood Protection Authority-East.” (In an email, John claimed that “the scientific consensus is that controlling the Mississippi River through the levee system is the primary reason for wetland loss, not canals and wells.”)

Barry did not believe that the industry would willingly contribute billions of dollars to coastal restoration. But he wondered whether it had any legal obligation to fund the master plan. When it ice-picked the marsh, did it break any laws? Barry thought it had. He knew that nearly every company that has operated in the marshes since the 1920s has used permits obliging them to maintain and repair any environmental damage it caused. In 1980, Louisiana began adhering to a federal law that required companies operating in the marsh — a list that includes ExxonMobil, ConocoPhillips, Shell, BP, Chevron and Koch Industries — to restore “as near as practicable to their original condition” any canals they dredge. After consulting with legal experts, Barry became convinced that most companies never filled in their canals and that the state had failed to enforce the law. In fact, many of the projects listed in the Coastal Master Plan called for plugging canals that should have been restored years ago.

“The reality is that our case is overwhelming,” Barry told me. “You look at the photographs of the damage, and you say, What the heck?” (This and the following quotation are paraphrases; indignation not only raises the volume of Barry’s voice, it also makes his language unfit for print.) “Are you out of your mind? They violated the terms of their contract. They broke the law!”

The levee board couldn’t enforce the law. But Barry believed that there was one way around its impotence: It could sue every single oil and gas company that had scarred the marsh in the last century. The complexity of such a case would be daunting, baroque. Lawyers would have to determine who dug every foot of the 10,000 miles of canals and pipelines and then quantify, in dollars, the extent to which each endangered New Orleans’s flood defense. The academic centers and environmental groups Barry contacted, while sympathetic to the cause, lost interest when they estimated how many millions of dollars would have to be spent on expert witnesses and coastal surveys. “We didn’t only need legal ability,” Barry said. “We needed the resources to take on Exxon, Shell, Chevron and BP — all at once.”

He compiled a list of private lawyers who have had success bringing major environmental lawsuits. It was a very short list. The first name on it was Gladstone N. Jones III, an attorney based in New Orleans who in 2006 won the largest judgment against the oil industry in the history of Louisiana: $57 million in damages for pollution and marshland loss caused by ExxonMobil. Jones, who resembles a midcareer Fred Gwynne and has the deep, cajoling voice to match, didn’t need to think long about taking the case. “It’s a pretty easy one to try, because the damage is so clear,” he told me. “I’ve never had a case where the industry acknowledges damage in their own papers. The science is irrefutable. The cause is irrefutable. The oil companies didn’t fill in the canals. Why? Because it cost money.”

Jones’s team of coastal experts, biologists and lawyers ultimately concluded that 97 corporations violated their permits over the last century. They hoped, perhaps quixotically, that after filing their lawsuit, other parishes and levee boards across the state would join the effort, with the goal of achieving a larger settlement with the entire industry. Barry thought the New Orleans levee board would serve as a “heat shield” to absorb the industry’s furor, providing other parishes the cover to file their own lawsuits. And cover was needed — there was no precedent for an environmental lawsuit of this scope and complexity. “There are few cases of this type in American history, where an environmental injury produced such significant human risk,” said Oliver Houck, a Tulane law professor who specializes in environmental law. “There’s nothing out there like this — not in the extent of the damage or the extent of the compensation claimed.” Jones couldn’t think of any precedent either. “New Orleans and the greater area will largely disappear over the next 50 years if nothing is done,” he said. “That’s not lawyer talk or political talk. It’s reality.”

On the morning of July 24, 2013, Barry announced the lawsuit at a news conference held in the Orleans Levee District’s safe house, a structure elevated 20 feet off the ground inside a warehouse built to withstand 180-mile-an-hour winds. Barry was unnerved by the ceremony of the event. He was a veteran of book tours and television interviews, but this was different. When it came time to deliver his main declaration, he stumbled, announcing that the board had filed a lawsuit against “97 oil and gas attorneys,” when he meant to say “companies.” He cursed into the microphone and reread the statement.

“From now on,” one of his lawyers said when they convened afterward, “I’m going to have my interns start my car.” Everyone laughed, except Jones. “This is going to get dirty,” he said.

“What are they going to do?” Barry asked. “Not buy my next book?”

Jones figured there would be a period of quiescence while the industry decided how to respond. Within hours, Jindal, who was in Aspen, Colo., at a meeting of the Republican Governors Association, released a statement. “This is nothing but a windfall for a handful of trial lawyers,” Jindal said, arguing that the suit came “at the expense of our coast and thousands of hardworking Louisianians who help fuel America by working in the energy industry.”

The fight over the lawsuit had entered a new phase. “I wasn’t surprised that Jindal opposed the suit,” Barry said, “but I was surprised by what happened next.”

“Louisianians who make money in oil buy politicians, or pieces of politicians, as Kentuckians in the same happy situation buy racehorses. Oil gets into politics, and politicians, making money in office, get into oil. The state slithers around it.” These sentences, written by A. J. Liebling in 1960 at the dawn of the deep-water offshore-drilling era, seem quaint when read today. Louisiana no longer slithers in oil; it drowns in it. It is also high on natural gas, thanks to the recent boom in hydraulic fracturing. And at some point along the way, the state, which has the oil and gas, ceded political control to the industry, which needs the oil and gas. Environmental activists have referred to Louisiana as “a petrocolonial state,” but for much of the last century, the petroimperium has largely been seen locally as a benign patriarch. Oil and gas is one of the state’s largest industries, responsible for 65,000 jobs. (An industry estimate, which takes into account “indirect” economic impacts, puts the figure at 300,000.) “If you want to know what the Louisiana economy might be without oil,” said Andy Horowitz, a history professor at Tulane, “look at Mississippi.”

Barry did not expect the support of Jindal, who has received more than $1 million in campaign contributions from the energy industry. But he did expect that Jindal would respond in a spirit of “malevolent neglect” — that Jindal would publicly oppose the lawsuit while grudgingly acknowledging his constitutional inability to block it. Jindal, after all, has been under pressure to fund the Coastal Master Plan, which he has promoted as “the largest effort in the nation to protect and restore a coastal landscape.” He had already directed state officials to commit every dollar of funding for the Restore Act — a federal law dedicating 80 percent of the fines paid by BP under the Clean Water Act — to the master plan.

A number of people close to the proceedings have said there were indications that some of the defendants were amenable to a settlement. Louisiana’s attorney general, Buddy Caldwell, suggested that discussions about a settlement were underway. A one-time contribution to the master plan might benefit the industry’s image and resolve any uncertainty about liability for coastal land loss. “They want to get all this stuff off their books,” Caldwell, referring to the energy industry, said on a local radio show. “And I believe after this legislative session, we’re going to see some big-time movement.”

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But soon after the lawsuit was announced, Jindal, who is widely expected to run for the Republican presidential nomination in 2016, indicated that he would go to unusual lengths to ensure that a settlement would never be negotiated. The nine-person levee board had been designed to gather experts and insulate them from political meddling. Now Jindal declared that he would refuse to appoint any candidates who supported the lawsuit. “To be very clear,” Garret Graves, then the chairman of the Coastal Protection and Restoration Authority, told a local reporter, “the governor has said that the lawsuit is a litmus test — period.” As it turned out, the chairman of the independent committee responsible for nominating candidates to the levee board, Jay Lapeyre, was the board chairman of ION Geophysical, a large oil and gas technology-service company.

Barry happened to be one of three members who was up for reappointment. Lapeyre began the next nomination meeting in October 2013 by saying he was under no pressure from Jindal’s office, but noted that Barry’s qualifications had to be reconsidered because the lawsuit had thrust him into “the political world.” “I don’t think there is any doubt that, except for the lawsuit, John Barry would be a shoo-in,” Lapeyre said. (Lapeyre has since confirmed this account.) The board did not vote to nominate Barry again.

In his place and for the other two seats, Jindal selected candidates who opposed the lawsuit and had little or no expertise in flood protection. Barry’s successor was Lambert Hassinger Jr., a New Orleans lawyer whose firm, Galloway Johnson, boasts of representing “several of the largest drilling contractors and pipeline-transportation companies in the world, as well as companies engaged in all phases of oil and gas production.” Once these appointments were made, a third of the levee board opposed its own lawsuit.

Barry might have concluded that after eight years of public service, it was time to focus his energies elsewhere. His book on Roger Williams had finally been published; for the first time in years, he could consider a new book. Instead, within days of being replaced on the board, he created his own nonprofit group, Restore Louisiana Now. Its mission was to “[preserve] the lawsuit and [prevent] opponents from getting the Legislature to intervene in what should be a court process.” He raised money for gasoline and a part-time assistant and set off on what resembled a statewide book tour, only instead of a book, he promoted the lawsuit. A lobbyist advised him to visit Rotary Club gatherings and the editorial boards of local newspapers. His tour took him to Monroe, near the Arkansas border; Lake Charles, near the Texas border; Houma, Lafayette and Shreveport. More than 300 people showed up at the Rotary Club in Baton Rouge, 60 in Ruston, seven in Chalmette. He delivered a presentation in which he explained the lawsuit’s rationale and showed before-and-after photographs of the marsh. He believed that he was making a difference. “We take seriously the responsibility we have to protect people’s lives,” he told Rotarians. “But how can we do that when we don’t have any resources?”

This March, the battle over the levee board’s lawsuit moved to Baton Rouge, where the Louisiana Legislature was entering session. Jindal appeared fixated on having the Legislature produce a bill that would kill the lawsuit before the courts could adjudicate it. But to do so, the bill would have to eliminate the right of the levee board to file a lawsuit in the first place. The bill would also have to go into effect retroactively, because the suit had already been filed. And the bill would have to pass in the next three months, after which the Legislature would be out of session for another year.

There are 105 seats in the Louisiana House of Representatives and 39 seats in the Senate. During the term, about 70 lobbyists from the oil and gas industry were in the legislative chambers. They worked in concert with the governor’s staff to secure support for a bill that would void the lawsuit. “They turned on the fire hose,” one veteran energy lobbyist said. “It was the best organized effort I have ever seen,” another said. Opposing them were 10 lobbyists hired by the law firms representing the levee board and the Sierra Club, which helped finance the effort. They were joined in Baton Rouge by Barry, Gladstone Jones and several other members of the board’s legal team.

Despite being so severely outnumbered, having little experience in state politics and being seen as an outsider even by members of his own coalition, Barry remained optimistic. If he could sway hostile crowds at Rotary Clubs, shouldn’t he be able to persuade enough legislators to kill a bill? Besides, legislators didn’t have to come out in favor of his lawsuit; they only had to agree to let the courts, not the Legislature, decide the case. There were other reasons to suspect that he had an advantage too. He had survived a smear campaign — he was called an “environmental extremist” (“That’s the worst smear they can think of in Louisiana”) and an “aspiring author” — and direct-action campaigns were being staged across Louisiana, criticizing the oil and gas industry’s meddling in state politics. Virtually every newspaper that published an editorial on the issue condemned the state’s effort to kill the lawsuit, including traditionally industry-friendly papers like The Lake Charles American Press, The Houma Courier and Acadiana Business. Three former governors of Louisiana came out in support of the lawsuit, as did a majority of southern Louisianians, by a margin of more than three to one — at least according to a poll commissioned by Restore Louisiana Now.

The intensity of the industry’s lobbying effort seemed to be backfiring, rousing the suspicion of some legislators, particularly those who were practicing lawyers. “If the industry doesn’t believe the levee authority has any standing to file a lawsuit,” said Representative John Bel Edwards, a Democrat from Roseland who is running to succeed Jindal as governor, “then they should go to court and file a motion. But rather than go to the courts, they ran to the Legislature. That was the first indication that the levee board’s claims were not frivolous at all, but had merit.” Senator Daniel Martiny, a Republican from Jefferson Parish who opposed the effort to destroy the lawsuit, put it more directly. “The bottom line is the oil industry has been a big supporter of a lot of people, myself included,” he said. “At times, I was even one of their heroes. And I had people way up in the oil-industry hierarchy tell me, We know you’re right about this, but we don’t have any other way to stop this.”

One by one, throughout the spring, bills written to kill the lawsuit failed — more than a dozen in all by the last week of the legislative session. Some of the bills were seen as overly broad, raising the fear that they might endanger the incipient BP settlement; others were voted down over constitutional concerns. In the final week of May, a lobbyist for the lawsuit told Barry, “If we voted today, we’d win.”

Louisiana grants its governor more powers than nearly any other state in the nation. One is the ability to veto any project in the state’s operating budget. During the final days of the legislative session, Barry watched helplessly as legislators who had pledged support for the lawsuit seemed to mysteriously change their minds. According to one pro-lawsuit lobbyist, Representative Gene Reynolds, a Democrat from Minden, told him that funding for a new roof for a V.F.W. hall in his district would be eliminated if he didn’t support a bill against the lawsuit. (Reynolds disputes this account. “My vote was based on information from my district,” he wrote in an email, “which depends heavily on oil and gas and the related benefits.”) Another pro-lawsuit strategist claimed that Senator David Heitmeier, a Democrat from Algiers who is an optometrist, had pledged his support for the lawsuit. When the time for the vote came, however, Heitmeier opposed the suit; a week later, Jindal signed a bill allowing optometrists to perform some minor eye surgeries — a pet cause of Heitmeier’s. (Heitmeier did not respond to repeated queries.)

While this was going on, oil executives with local political influence showed up in the legislative chambers “to watch, to be muscle,” as the lobbyist put it. The Houma delegation was visited by a senior BP lobbyist. Although Houma is the seat of Terrebonne Parish, one of the most endangered of the coastal parishes, all of its legislators emerged from their conversations in favor of the bill. “You could feel the weight coming down,” Barry said. “You could see them getting peeled off one at a time, through threats or promises. It was disheartening.”

Many legislators didn’t need to be persuaded. In late May, Senator Robert Adley, a Republican from Benton, told one reporter: “I think it’s absurd to say that the oil and gas industry has damaged the coast. They did what they were told to do.” This is a claim that most industry representatives have not been brazen enough to make. Then again, Adley himself is an industry representative. Since 1993, he has been the owner of the Pelican Gas Management Company, and before that he was the president of ABCO Petroleum for 20 years.

Adley is not the only one. State legislator is a part-time job, and many work in the oil and gas industry, too. Representative Gordon Dove, a Republican from Houma who is the chairman of the Committee on Natural Resources and the Environment, owns Vacco Marine, which provides vacuum trucks for the cleaning of oil tanks and has received many complaints from environmental regulators. Representative Neil Abramson, a Democrat from New Orleans, is a lawyer who has defended oil and gas companies in environmental-damages lawsuits. Representative Jerome Richard, an independent from Thibodaux, is a sales manager for Byron E. Talbot, a contractor employed by Chevron. Representative James Morris, a Republican, is an independent oil producer from Oil City.

But many of these legislators also live in coastal parishes and have watched for years as the lands they represent steadily disappeared. Richard’s district includes Lafourche Parish, which has suffered some of the most extreme land loss in the state, with an especially high proportion of that loss coming from canals dredged by the industry. Richard didn’t like the idea of a bill that would kill a lawsuit already in progress and pledged his support to Barry. But he ultimately decided that such a bill would be constitutional, and everyone else in his delegation opposed the lawsuit, so he went along. “I didn’t want to be the only one voting against it,” he told me.

Adley spoke for many critics of the lawsuit when he said he was convinced that none of the 97 oil and gas companies had done anything illegal. He cited as proof testimony given before a Natural Resources Committee meeting by J. Blake Canfield, an attorney for the state’s Department of Natural Resources, who said, “We do not have any evidence that the permits have been violated.” Canfield, however, also added that the state had not looked into permits older than 1980. Chris John, the president of the L.M.O.G.A., the industry lobby, makes a different argument. The lawsuit, he wrote to me in an email, will endanger the Coastal Master Plan: “Litigation will actually slow the process of addressing coastal land loss. This is a bad result for the community.”

I asked Adley whether he thought his position as an oil executive might constitute a conflict of interest. After all, Senator Eric LaFleur, a Democrat from Ville Platte and a lawyer at the firm that represents the Louisiana Oil and Gas Association, recused himself from all votes related to the lawsuit for this reason. Adley’s voice sharpened: “I’m elected by the people in my district. They know who I am. They know what industry I’m in. They choose to send me there. It’s their right to make that decision — not yours, not anyone else’s. People in the oil and gas industry do support me because, yes, I’ve been in the industry and, yes, I understand them. That’s important to them.” He continued: “Let me tell you something: There are a whole lot of people in this state that have raised their children and got their education based on their experience in the oil and gas industry. At one time, 70 or 80 percent of our entire budget and employment came from that industry. If you took all those people out of the government here, you wouldn’t have much left.”

Jindal’s best remaining chance to kill the lawsuit took the form of a bill that was introduced by Senator Bret Allain, a Republican from Franklin, and written primarily by Jimmy Faircloth, Jindal’s former executive counsel. But when it looked as though it would not make it out of the Senate Judiciary Committee, Adley, a member of that committee, pulled off an unusual — and, Gladstone Jones has since argued before the Federal District Court for the Eastern District of Louisiana, unconstitutional — maneuver. He reassigned it to Allain’s Natural Resources Committee. There it replaced the text of a different bill. The switch occurred so quickly that those who were sitting in the Natural Resources Committee room, including Barry, were told that no written copy of the bill was available for public review, but the committee voted to send the bill to the full Legislature. Allain was candid about the intent of his bill. Just as Jindal spoke openly about his determination to prevent the lawsuit from proceeding and just as Lapeyre admitted that Barry’s role in the lawsuit was sufficient to deny him renomination, Allain announced that his goal was “to kill the lawsuit.”

Once it became clear that the bill would pass, some peculiar votes — or nonvotes — followed. Abramson, the oil and gas lawyer from New Orleans, declined to vote. Senator J. P. Morrell, another New Orleans lawyer and a Democrat, voted for the bill and later said that he had not been present for the vote and that his machine had malfunctioned. Senator Gregory Tarver, a Democrat from Shreveport, told a pro-lawsuit lobbyist that he had voted for the bill by accident. No one who voted against the bill claimed it was by accident.

One peculiarity about the fight over the lawsuit is that few industries are in greater need of coastal restoration than oil and gas. The next major hurricane that hits the Gulf Coast will put at risk billions of dollars of industry infrastructure — refineries, oil tanks, terminals and pipelines. This is why the industry endorsed the Coastal Master Plan. A second oddity is that Jindal, a hero of the anti-tax faction of the national Republican Party, who last year tried to eliminate the state’s corporate and income taxes, has now put himself in the position of allowing the largest single bill facing his state — for the balance of the Coastal Master Plan — to fall almost entirely upon taxpayers.

The industry, by trying so strenuously to destroy the lawsuit through an act of the Legislature, may have finally overplayed its hand. “Louisiana has lost a couple of its gods in the last decade,” Oliver Houck, the Tulane law professor, told me. The first god was the Army Corps of Engineers, which once could do no harm. Hurricane Katrina put an end to that. The BP oil spill, and the company’s inept early response in its aftermath, shook local confidence in the industry for the first time in generations. The fight over the lawsuit represents a new milestone. “There’s been a sea change in public opinion,” Houck said. “I don’t think [the industry will] ever recover the kind of uncritical acceptance that they have enjoyed in Louisiana for the last century.” As Barry said: “The idea of making the industry live up to its legal responsibility is not going to die.”

The lawsuit, however, might. Gladstone Jones has requested that a federal judge rule on whether the bill signed into law by Jindal is constitutional and indeed restricts the lawsuit from proceeding. Judge Nannette Jolivette Brown of Federal District Court will hear that motion, along with motions filed by energy companies to dismiss the suit, on Nov. 12. At the same time, Jindal continues his effort to replace levee-board members with lawsuit opponents. He has appointed four board members so far, which leaves the board with a slim 5-to-4 majority, at least for now, in favor of its own lawsuit.

Should the lawsuit fail one way or another, Jindal will find himself under tremendous pressure to offer an alternative method of funding the master plan. Even Jerome Zeringue, the current chairman of the state’s Coastal Protection and Restoration Authority, acknowledges that the oil industry will have to make a significant contribution. “We’re in no way denying the fact that there’s some culpability,” he told me. “Obviously they recognize this and have admitted there’s a liability based upon that.” Without the threat of a lawsuit, Jindal will have to negotiate a deal with the industry himself. Or he can delay until his second term ends, in January 2016, and let his successor deal with it.

A backup plan would be for the attorney general, Buddy Caldwell, to file a lawsuit on behalf of the state. This is the path advocated by Houck, Representative Richard and many others, but few in the state expect Caldwell to do any such thing. Another possibility is for a group of residents to file a class-action lawsuit demanding restitution from the industry. Though no specific path seems as effective as the original lawsuit, Barry remains optimistic. He has spoken privately about his backup plans. He refers to them as Plan B, Plan C, Plan D and Plan E. “Plan F,” he said, “is moving out of New Orleans.”

Barry originally pledged not to write about the lawsuit, mainly because so many opponents accused him of having ulterior motives for joining the levee board in the first place. (“I believe that this entire issue is really put together for a few trial attorneys and one guy who’s writing a book,” Senator Adley told me. “Today you and I have had the pleasure of adding one more chapter to his book.”) Barry forced himself not to take notes about his experiences over the last several years to avoid the temptation to write a book.

He is now reconsidering. The book would be a kind of sequel to “Rising Tide,” about “the interplay between the river, the sea, politics and oil over the last century.” Though it would “be about a lot more than the lawsuit,” he said, the story would most likely culminate with the battle to make the industry pay for its share of the Coastal Master Plan. In this climactic chapter, a figure named John Barry would appear on the scene. But John Barry, John Barry insists, would be just a minor character.