In July 2015, Wisconsin’s Supreme Court shielded Gov. Scott Walker, then a rising Republican star with aspirations to the presidency, from a criminal investigation.

The court’s conservative majority halted the probe into what prosecutors suspected were campaign finance violations. One of the deciding votes was cast by Justice David Prosser, a conservative who had won reelection a few years earlier in a heavily contested race. During the race, a state GOP operative said if their party lost Prosser, “The Walker agenda is toast,” according to an email included in a trove of documents the Guardian surfaced. Another vote for Walker came from Michael Gableman, a justice who had also waged a contentious campaign for his Wisconsin Supreme Court seat.

The high court, determining the prosecutors had overreached, ordered the investigation’s documents destroyed. But not before the Guardian got its hands on a copy. And buried in the 1,500 pages was a reference to a key figure in propelling both Prosser and Gableman to victory: the co-chair of the right-leaning legal group the Federalist Society, organizer of dark money groups and conservative strategist Leonard Leo.

The Prosser and Gableman races were crucial skirmishes in Leo’s decadeslong, ambitious effort to shape American law from the ground up. It’s a project whose full dimensions are only now becoming clear. ProPublica detailed the arc of Leo’s activism in a recent story and podcast with “On The Media.”

If Leo’s name sparks a note of recognition, it’s usually because he was Donald Trump’s judge whisperer and a leading figure in helping create the 6-3 conservative supermajority on the U.S. Supreme Court. Leo realized decades ago it was not enough to have a majority of Supreme Court justices; he would have to approach the legal system holistically if he wanted to bring lasting change. To undo landmark rulings like Roe v. Wade, Leo understood that he needed to make sure the court heard the right cases brought by the right people and heard by the right lower court judges.

Leo built a machine to achieve that goal. He helped ensure the nominations of justices from Clarence Thomas to Amy Coney Barrett. He used his closeness to the justices to attract donors to support his larger effort. He then used those donations to build a network of dark money groups supporting his candidates and causes across the U.S. And he helped elect or appoint state Supreme Court justices who were predisposed to push American jurisprudence to the right.

Wisconsin was where Leo honed his strategy. In 2008, in a racially charged challenge to the state’s first Black Supreme Court justice, Leo himself raised money for Gableman, according to a person familiar with the campaign. Leo passed along a list of wealthy donors with the instructions to “tell them Leonard told you to call,” this person said. All those people gave the maximum. Gableman won, the first time an incumbent was unseated in Wisconsin in 40 years. (Leo declined to comment to us on his role in that race.)

Then in 2011, state GOP operatives turned to Leo to boost Prosser. They hoped he would help them raise $200,000 for “a coalition to maintain the Court,” the emails show. Prosser won, by half a percentage point. (When the emails mentioning his race surfaced, Prosser defended his independence.)

In 2016, Leo got involved again. Walker had a vacancy to fill and had three people on his shortlist: two Court of Appeals justices and the former attorney for an anti-abortion group and Federalist Society chapter head, Dan Kelly. “Leo stepped in and said it’s going to be Dan Kelly,” a person familiar with the selection told us. Walker denied speaking to Leo, who said he didn’t remember. From 2016 until the present, a group called the Judicial Crisis Network (which is now known as the Concord Fund), was a regular donor to state judicial races. Leo has no official role at the JCN, which as a dark money group does not have to disclose its donors. But he helped create and raise money for it, and JCN often works toward the same goals as the Federalist Society.

JCN was a crucial financial supporter of the public campaigns to win support for Supreme Court nominees backed by Leo, from Chief Justice John Roberts to Samuel Alito, Neil Gorsuch, Brett Kavanaugh, and Coney Barrett. In Wisconsin, JCN sent increasing amounts of money to judicial races through circuitous routes. Sometimes the contribution flowed through a national political organization like the Republican State Leadership Committee. Other times, the money was sent to Wisconsin-based outfits.

Wisconsin is not the only state that Leo focused on. North Carolina shows the effects of more than a decade’s worth of big-dollar funding from his network and a torrent of negative ads questioning the integrity of the judiciary.

In 2022, after years of sustained campaign spending by the Judicial Crisis Network and allied groups, North Carolina’s high court flipped from a 4-3 Democratic majority to a 5-2 Republican majority. Months later, the court did something extraordinary: It reinstated a voter ID law that the same court, in its Democratic-led iteration, had found discriminated against Black voters. It also overturned a newly court-approved elections map that had produced an electoral outcome reflecting the state’s partisan split.

In Wisconsin, the battles over the high court continue to be fierce. In April, Kelly, Leo’s chosen candidate, ran to maintain a conservative majority on the Supreme Court. It was the most expensive judicial race in U.S. history, with both sides spending at least $51 million. But Democrats were activated by the U.S. Supreme Court’s ruling to overturn Roe and by election maps that had maintained Republican dominance in the Legislature in a state evenly divided along partisan lines. Their candidate, Janet Protasiewicz, won resoundingly.

But that hasn’t stopped Republicans from trying to regain control. In September, there was talk of impeaching Protasiewicz because of comments she made during the campaign about “rigged” election maps. That effort has subsided — for now.

Leo’s candidate lost in Wisconsin — but his efforts over the years have succeeded in something else: transforming seats on state Supreme Courts into political prizes. In many states, such judges are no longer viewed as independent arbiters from a branch of government that operates outside partisanship but as a kind of super-legislator. “That’s bad for the system,” Robert Orr, a former Republican North Carolina justice, told us. “It’s bad for democracy. It’s a very dangerous path to tread down.”

In a written statement, Leo said state courts “are more independent and impartial today than they were when trial lawyers and unions dominated state judicial races without any counter.”

The stakes for democracy are stark. Already, a University of Washington study ranking the health of democracies in states found North Carolina and Wisconsin have plummeted from two of the highest-scoring states to scraping the bottom.

One result of this project is clear. Today, the practice of deploying every weapon in the American political arsenal, from nasty campaign ads to spending by groups whose donors are hidden, is now a routine aspect of campaigns for the judges who rule on state laws and, in 2024, might well decide the outcome of elections in battleground states.