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Joe Mendelson didn’t seem like the kind of person who would upend the entire environmental movement in pursuit of a legal strategy to attack climate change. In 1999, he was a young public interest lawyer working at an obscure organization, the International Center for Technology Assessment. But, bucking the conventional wisdom of bigger environmental groups, Mendelson took the momentous step of filing the petition that led to the groundbreaking Supreme Court ruling in Massachusetts v. United States Environmental Protection Agency.

That landmark 2007 decision—which has been described as the most significant environmental case in U.S. history—pushed the EPA to regulate carbon dioxide under the Clean Air Act. That gave advocates a mechanism to force a recalcitrant government to address climate change.

The Clean Air Act, signed into law by President Richard Nixon in 1970, requires the EPA administrator to regulate “emissions of any air pollutant” from new motor vehicles that contribute to “air pollution which may reasonably be anticipated to endanger public health or welfare.” Mendelson’s petition argued that carbon dioxide fit these criteria. The upshot: The EPA must regulate it.

In his gripping new book, The Rule of Five, Richard J. Lazarus, a law professor at Harvard University, weaves the tale of how Mendelson’s petition led to the landmark decision, how he brought along the other environmental advocates despite bitter infighting, and how missteps by their opponents gave the lawsuit wings. Lazarus, who interviewed participants in the case, from lawyers to Supreme Court justices, writes like a novelist. Discussions of the so-called Chevron doctrine and “parts per billion” go down easy, enhancing the narrative rather than interrupting the flow.

There was nothing inevitable about Mendelson’s petition succeeding. Bill Clinton’s EPA, wary of addressing climate change before the election, decided to leave it for the Gore administration. Sadly, as we know, there was no Gore administration. With only a few weeks left before George W. Bush took office, however, the EPA administrator, Carol Browner, decided to move the petition forward. Lazarus recounts how one departing Clinton appointee described this final action: It was like “leaving a turd on the door of the next [administration].”

The big environmental groups grudgingly decided to work with Mendelson to try to control the process and avoid a catastrophic loss. Initially they had some help from Browner’s successor, Christine Todd Whitman, as well as from President Bush himself, who had pledged in his campaign to address climate change. But Bush’s vice president, Dick Cheney—a former oil executive and ardent deregulator—outmaneuvered them both. First, he organized a group of Republican senators to send a letter to the president demanding a formal White House position on carbon dioxide and climate change. Then, preempting any review process, he drafted a response from the president, got it signed, and delivered it to the Hill, all before Whitman could brief her boss or rally her allies.

Cheney, however, had made a fatal miscalculation. By “rushing a presidential decision,” Lazarus explains, “Cheney failed to allow for any consultation with the expert lawyers at the EPA.” Those lawyers would have told him that his argument was legally deficient and might set his case up for failure.

Moreover, even when the administration could have pulled back, Cheney and the political appointees at the EPA wanted more, to kill off any chance for future regulation of greenhouse gases. So instead of burying Mendelson’s petition, they decided to act on it. They denied the petition, sending a clear signal that the Clean Air Act did not allow any such regulation, again using broad language that would doom their case in the coming years. With that denial, they gave Mendelson the power to appeal the ruling, moving the case from the EPA to the courts.

What happened next is a classic of liberal politics: Once the die was cast and the case had been filed, the environmental groups realized they needed to stick with it in order to shape strategy and tactics—and to try to take credit for a victory.

Plenty of road bumps remained. After losing in the D.C. Circuit, the environmental groups wanted to abandon the case. Because the court’s ruling was so fractured, it had not struck a definitive blow against regulating carbon dioxide in the future. The groups thought it was best left there. But once again, there was one lawyer who disagreed and was able to circumvent the others. This time it was Jim Milkey, the lead attorney on the case for Massachusetts. Not wanting to give up the fight—or the lead role played by the state—he convinced the Massachusetts attorney general to file a writ of certiorari with the Supreme Court to appeal the lower court’s ruling. There were bitter recriminations and angry denunciations among the environmental lawyers. But the groups came around, because if the Court took the case, they wanted to be in the game.

The Supreme Court takes very few cases, as Lazarus explains. They receive thousands of requests each year and agree to hear only 60 or 70 of them. Massachusetts v. EPA overcame these vanishingly small odds in part by excellent brief writing by the brilliant law professor Lisa Heinzerling, whom the environmentalists had chosen. In her masterful petition, she achieved something no one else had: getting all the green groups to agree unanimously on a legal strategy.

The petition argued that carbon dioxide fit the criteria outlined by the Clean Air Act. The upshot: The Environmental Protection Agency must regulate it.

Their appeal to the Court also succeeded thanks to a flawed brief on the other side. The U.S. Office of the Solicitor General had made a signal error—that of suggesting the case was important. The best way to defeat a petition is to argue that the case doesn’t merit Supreme Court review. Surprisingly, the office took the opposite tack and asserted a broad legal theory “by suggesting the EPA’s discretionary authority had not been limited ‘in any way’ ” by Congress. Recognizing a gift, the environmental groups trumpeted the statement’s breathtaking impact. They argued that the Office of the Solicitor General’s legal argument would have “sweeping ramifications for executive branch authority.” The Supreme Court took the case.

However, the comity between the environmental lawyers collapsed as they argued over which of them should present the oral argument in court. Arguing before the Supreme Court is a singularly prestigious role, and something most lawyers only aspire to. Those who do manage to get there boost both their salary and their professional status. While most of the lawyers favored Heinzerling for this role, Milkey pulled rank as the lawyer representing the lead plaintiff, the State of Massachusetts, and refused to cede the role.

Lazarus puts us in the courtroom for oral arguments. As the Court was called to order, all eyes were on Milkey. Aware of Justice William Brennan’s “rule of five”—in a court of nine, you need five to win—Milkey knew that Anthony Kennedy, the usual swing vote, was a critical player in any victory. But first he had to parry Antonin Scalia’s hostile questions: How could he show imminent harm from automobile emissions? Weren’t U.S. emissions just a small fraction of the world’s emissions? How would limiting them address global climate change? Both sides fought for Kennedy’s favor, with the liberal justices posing questions that helped direct Milkey to make the right points. Milkey’s preparation and quick-wittedness made his “allies” amend their views—even if it didn’t mend tattered friendships—and as oral arguments concluded, it seemed possible that the environmentalists had won.

And, in fact, they had. Lazarus tells us how John Paul Stevens brought Kennedy to his side to forge a majority in favor of Massachusetts, writing a broad opinion affirming the EPA’s authority to regulate greenhouse gases. “The Court’s ruling,” Lazarus writes, “would make history.”

But history follows a tangled path. Barack Obama’s environmental team acted on many fronts; while stymied by a Republican-controlled Congress after the 2010 midterm elections, the president used his executive authority to pursue new regulations, including rules on motor vehicle emissions and a bold plan to regulate power plants. He successfully used the international stage to press other nations to pursue similarly ambitious goals in the Paris Agreement in 2015.

With the election of Donald Trump, all of this is in the process of being undone. As Lazarus acknowledges at the end of Rule of Five, “the kind of transformative change that Massachusetts sought to trigger can begin in a courthouse, but it never ends there.” For Lazarus, the legal drama shows how one person can help set the stage for victory, even while true victory requires an engaged citizenry. The “rule of five” is only effective in the long run if you have the voters on your side.