Last week, five Democratic senators sent disturbing missives to three Trump administration officials about secret forces transforming the US courts and about one very powerful American lawyer in particular, Leonard Leo.

You may know Leo’s name if you’re steeped in the dramas of politics and law or were paying attention to the Supreme Court nominations of Neil Gorsuch and Brett Kavanaugh, which he helped orchestrate. He is co-chair of the conservative and libertarian legal advocacy group known as the Federalist Society, an organization recently described in the New York Times as “a juggernaut for propelling the courts to the right.”

And it is Leo’s involvement in the judge-and-justice-picking process that prompted the senators’ letters.

Attorney general Bill Barr, Office of Personnel Management director Dale Cabaniss, and White House counsel Pat Cipollone all got mail. Senators Sheldon Whitehouse, Richard Durbin, Sherrod Brown, Richard Blumenthal, and Mazie Hirono signed on, saying Leo’s involvement in nominating jurists while likely profiting from related fundraising activities raises concerns about conflicts of interest.

They want to see governmental communications with Leo while considering new legislation on this topic.

All roads lead to Leo

Leo is at the center of a complex network of nonprofits and shell entities funded largely by anonymous donors, which the senators say is problematic. That network collected $250 million in donations between 2014 and 2017, much of which funded ads promoting judicial nominations. He appears to also have a financial interest in these advocacy efforts yet won’t disclose those earnings.

If Leo had been a federal government employee, officially, consulting with the president about judicial nominees, he would have been subject to disclosure rules that could have illuminated potential conflicts. They also believe that if Leo didn’t qualify as an employee, his services most likely exceeded what the federal government can accept voluntarily, and may have violated restrictions on access to non-public records, too.

Still, Leo is just one guy, albeit one with considerable pull in politics and on pursestrings. To understand why his activities matter so much—why they represent a threat to the “bedrock American principle of equal justice under the law” as the senators claim—we must travel back to the last century, when the Federalist Society was a mere contrarian idea, just a twinkle in the eyes of right-inclined law students.

The little dissenters that could

In its own words, the Federalist Society was created in 1982 by three aspiring lawyers to counter the “orthodox liberal ideology which advocates a centralized and uniform society” and “strongly” dominated the legal profession and law schools. Now, the group boasts 70,000 members and is arguably the most powerful force in American jurisprudence.

Still, it hasn’t abandoned the tone of a scrappy minority fighting a progressive orthodoxy. “While some members of the academic community have dissented from these [liberal] views, by and large they are taught simultaneously with (and indeed as if they were) the law,” the society’s website complains.

This characterization is too humble, however, and woefully incomplete. It ignores the society’s actual enormous influence.

Five of nine high court justices are members, after all. Four of them—chief justice John Roberts, Samuel Alito, Gorsuch, and Kavanaugh—benefited from Leo’s advocacy on their behalf, as his bio notes. Clarence Thomas, Roberts, Gorsuch, and Kavanaugh have all spoken at recent Federalist Society events.

The organization’s sway can’t be overstated. The society advances an approach to legal interpretation known as textualism or originalism. Basically, textualists promote a strict reading of the law adhering to the original writers’ intent, as opposed to a take that considers social change. This literal approach has influenced lawyering across ideologies, and in 2015 progressive Supreme Court justice Elena Kagan credited Federalist Society hero, her colleague the now deceased Antonin Scalia, with turning everyone into a textualist, more or less.

Practically, as the society’s intellectual influence has grown, so has its fundraising network, along with its political power. Now, Trump, with the aid of Senate majority leader Mitch McConnell, has appointed an unprecedented number of federal judges, nearly 200. Most of them—85% of his appellate court nominees—are Federalist Society members.

As the president himself noted at last month’s state of the union address, the most impressive of these gets are his high court picks, Gorsuch and Kavanaugh. Both participated in the Federalist Society’s 2019 lawyers’ convention in November, with Kavanaugh headlining the opening event and Gorsuch closing the conference.

Before Kavanaugh gave his address, McConnell celebrated the Republican court-packing project to standing ovations from a sea of thousands of conservative attorneys. Former White House counsel Don McGahn, a member as well, also spoke.

In other words, the Federalist Society is no joke. Its membership roll boasts the most powerful lawyers in American politics and beyond. It has allies in all the highest places.

That would not be a problem if it was just a group of conservative nerds into close reading. But that’s not all they are, according to Whitehouse, and others.

“The American people ought to know who’s influencing their courts,” the senator told Quartz in an email. “There is a dark money campaign by partisan donor interests to capture our judiciary.”

Friends, enemies, and frenemies of the courts

Leo and the Federalist Society play a key role in that shady project, court commentators argue. Whitehouse and colleagues have been trying to shine a light on these “unprecedented and weird” developments, as he puts it, with limited success.

Last year, for example, the senator—along with Hirono, Durbin, Blumenthal, and Kirsten Gillibrand—filed an amicus brief in a controversial New York gun rights case before the high court. It caused a stir but in no way deterred conservatives.

“The Federalist Society’s Executive Vice President, Leonard Leo, has been linked to a million-dollar contribution to the NRA’s lobbying arm, and to a $250 million network largely funded by anonymous donors to promote right-wing causes and judicial nominees,” the lawmakers wrote.

They urged the justices to drop the divisive Second Amendment matter, which a change in local legislation arguably rendered moot anyway. Otherwise they risked eroding the public’s trust in judicial impartiality. The senators warned the court that deciding the case unnecessarily would turn the tribunal into a conservative tool, with the justices acting as puppets for groups that promised donors that their new guys, Gorsuch and Kavanaugh, would deliver the desired decisions on highly polarizing issues.

The Wall Street Journal editorial board was outraged by the lawmakers’ filing, calling it an “enemy of the court” brief. It defended the Federalist Society as a “network of bookish conservative-leaning students and lawyers” that couldn’t possibly influence politics.

“The Federalist Society doesn’t file amicus briefs. Its efforts are devoted to educational events and debates on public policy and law, and they aren’t secret. Liberals are welcome. If Mr. Whitehouse were interested in learning about opposing views, he might be too,” the board protested.

McConnell and Republican senators also joined the fray, sending the justices a strange letter reassuring them that they were safe from threatening Democrats. The justices, of course, did not respond to any of the brouhaha, at least not directly.

They didn’t drop the case and are expected to issue a decision in the hotly-debated matter by term’s end in late June. And their docket is packed with controversies—like last week’s arguments about abortion restrictions—that the left says have been designed specifically for review by the new conservative bench to overturn precedent.

So Whitehouse isn’t moved by the society’s defenders. Sure, some members are just intellectuals advancing a certain preferred legal philosophy. “That’s all fine, but it’s not the whole story,” he contends.

Leo’s central role in an anonymous fundraising network designed to influence the courts, Trump’s acknowledgment that the Federalist Society “picked” his judges, and McGahn’s admission that he sees the group as “in-sourced” to the White House to handle judicial selection, all show there’s more to the organization than spirited legal debate. Whitehouse suspects undue and untoward influence that he says undermines the rule of law itself.

If he could follow the money, maybe he could conclusively prove it. So far, however, the senators haven’t heard from administration officials they addressed for records, providing an April 3 deadline, or from the Federalist Society. (The Justice Department didn’t respond to Quartz’s request for comment).

“It’s an obvious problem when an anonymously-funded private organization has this role,” Whitehouse says. “And it’s improbable that this secretive quarter-billion-dollar dark money network would be engaged in these covert activities without ulterior motives.”