In the 2024 election cycle, over $2.8 billion in political spending came from sources that disclosed no donors. The money funded attack ads, voter mobilization, and issue campaigns across every contested race in America. The public has no way to know who paid for it.
This is dark money — political spending routed through organizations that are not required to disclose their funders. It is legal. It is growing. And it has fundamentally changed how American democracy operates.
What is dark money?
Dark money is political spending by organizations that do not disclose their donors. The term describes money flowing into elections through nonprofits classified under Section 501(c)(4) of the tax code — groups the IRS defines as "social welfare organizations."
These groups can spend unlimited amounts on political advertising and voter contact as long as politics is not their "primary purpose." The IRS has never defined what percentage of activity counts as primary. In practice, 501(c)(4)s operate as political vehicles that hide their funders.
Unlike super PACs — which must disclose donors — or traditional PACs — which face contribution limits — dark money groups operate in a disclosure gap created by outdated tax law and a 2010 Supreme Court decision that treated political spending as speech.
The result: a parallel campaign finance system where the biggest checks are written by people whose names never appear in public records.
Direct contributions: Money given directly to candidates. Limited to $3,300 per election. Fully disclosed.
Super PAC spending: Unlimited independent expenditures. Must disclose donors, but can accept money from dark money groups.
Dark money: Spending by 501(c)(4) nonprofits. No donor disclosure required. No spending limits.
How dark money flows into elections
The path from donor to voter is deliberately obscured. A wealthy individual or corporation writes a check to a 501(c)(4) nonprofit. That group either spends the money directly on political ads, or transfers it to a super PAC, which then discloses the nonprofit as its donor — but not the original source.
This is called "dark money laundering." The super PAC's disclosure reports show a donation from, say, "Americans for Prosperity" — a 501(c)(4) funded by the Koch network. The public sees the nonprofit's name. The original donors remain hidden.
According to OpenSecrets, the nonpartisan research group that tracks campaign finance, dark money groups spent $1.5 billion directly on political advertising in 2024. Another $1.3 billion was transferred to super PACs, where it appeared in disclosure reports as coming from the nonprofit, not the underlying funders.
The system works because the IRS does not require 501(c)(4)s to disclose donors, and the Federal Election Commission has repeatedly failed to close the loophole. A 2018 Treasury Department rule change under the Trump administration made it easier — dark money groups no longer have to report their donors even to the IRS.
Citizens United and its aftermath
The modern dark money system began with Citizens United v. FEC, the 2010 Supreme Court decision that struck down limits on corporate and union political spending. The 5-4 ruling held that independent political expenditures are protected speech under the First Amendment.
Justice Anthony Kennedy, writing for the majority, assumed disclosure would provide accountability. "With the advent of the Internet, prompt disclosure of expenditures can provide shareholders and citizens with the information needed to hold corporations and elected officials accountable," he wrote.
That assumption was wrong. The decision opened the door to unlimited spending, but existing tax law already provided a way to hide the spenders. Within months, political operatives realized 501(c)(4) nonprofits could spend unlimited amounts on elections without disclosing donors — and the FEC lacked the votes to stop it.
Dark money spending exploded. According to the Brennan Center for Justice, dark money groups spent $5.2 million in the 2006 midterms. By 2012, that figure hit $300 million. In 2020, it reached $1 billion. The 2024 cycle set a new record.
The court's conservative majority has shown no interest in revisiting the decision. In 2021, the court upheld disclosure requirements in a California case — but only for groups whose "major purpose" is political activity. The IRS has never enforced that standard against 501(c)(4)s.
The Leonard Leo network
No single figure embodies the dark money system more than Leonard Leo, the Federalist Society operative who built the conservative legal movement's judicial pipeline. Leo pioneered the use of interlocking dark money groups to fund everything from Supreme Court confirmations to state judicial races.
In 2021, Leo received a $1.6 billion donation from electronics manufacturing magnate Barre Seid — the largest known political gift in American history. The money went to the Marble Freedom Trust, a 501(c)(4) Leo controls. The donation was structured to avoid all taxes and disclosure requirements.
According to a 2024 ProPublica investigation, Leo's network has spent over $500 million since 2020 on judicial confirmations, state attorney general races, anti-abortion ballot measures, and media campaigns targeting Democratic officials. None of the spending disclosed its original funders.
The network operates through a web of interconnected nonprofits with names like the Judicial Crisis Network, the Concord Fund, and the 85 Fund. Money moves between them in ways designed to obscure the trail. A donor gives to one group, which grants to another, which spends on politics. By the time the money reaches voters, its source is untraceable.
Leo's model has been replicated across the political spectrum. Liberal dark money groups like Arabella Advisors' network spent over $1.2 billion in the 2020 cycle using the same structure. The difference: Leo's network focuses on judicial appointments and long-term institutional power. The Arabella network funds issue advocacy and voter mobilization.
Both sides now depend on dark money. The system Leo perfected is bipartisan infrastructure.
How dark money shapes policy
Dark money does not just fund campaigns. It builds the intellectual and legal infrastructure that shapes policy long before voters cast ballots.
Conservative dark money funds the network of state-level policy groups that draft model legislation on everything from abortion bans to voting restrictions. The American Legislative Exchange Council (ALEC), a 501(c)(3) nonprofit, produces template bills that state legislators introduce as their own. ALEC's funders include Koch Industries, ExxonMobil, and pharmaceutical companies — all disclosed only because of leaked documents, not legal requirements.
On the left, dark money funds climate advocacy, reproductive rights organizing, and voting rights litigation. The Sixteen Thirty Fund, part of the Arabella network, spent $410 million in 2020 on ballot measures, issue ads, and voter registration. Its donors remain unknown.
The policy impact is measurable. A 2023 Brookings Institution analysis found that states where dark money groups spent heavily on judicial races saw significant shifts in case outcomes on issues like environmental regulation, labor rights, and corporate liability. The money didn't just elect judges — it changed the law.
At the federal level, dark money shapes Supreme Court confirmations. The Judicial Crisis Network spent $35 million on ads supporting Brett Kavanaugh and Amy Coney Barrett. The source of that money has never been disclosed. The justices those ads helped confirm now issue rulings that affect 330 million Americans.
This is the core problem: dark money allows a small number of wealthy individuals and corporations to shape policy in ways the public cannot see or hold accountable. The voters affected by those policies have no way to know who paid to create them.
What transparency would look like
Ending dark money does not require a constitutional amendment or overturning Citizens United. It requires Congress to pass disclosure laws and the IRS to enforce them.
The For the People Act, which passed the House in 2021 but died in the Senate, would have required any group spending over $10,000 on political ads to disclose donors who gave more than $10,000. It would have closed the 501(c)(4) loophole by requiring disclosure for any political spending, regardless of the group's tax classification.
The bill had 49 Senate votes. It needed 60 to overcome a filibuster. It has not been reintroduced.
State-level reforms offer a preview of what national transparency could achieve. Montana passed a dark money disclosure law in 2015 requiring any group spending over $500 on state elections to disclose donors. According to the National Institute on Money in Politics, dark money spending in Montana legislative races dropped 73 percent in the first cycle after the law took effect.
The law survived a court challenge. The groups that opposed it did not argue disclosure was unconstitutional — they argued Montana's threshold was too low. The court upheld it.
Full transparency would require three changes:
Real-time disclosure. Any group spending over $10,000 on political ads must disclose donors within 48 hours. Current FEC rules allow delays of up to 60 days — long enough for an election to be over before the public knows who paid for it.
Source disclosure. Super PACs must disclose not just the nonprofit that gave them money, but the original donors to that nonprofit. The current system allows one layer of anonymity. Full transparency requires tracing money to its source.
IRS enforcement. The IRS must define "primary purpose" for 501(c)(4)s and enforce it. If a group spends more than 50 percent of its budget on politics, it is a political organization and must disclose donors. The current standard — whatever the group says its purpose is — is not a standard.
These reforms would not limit spending. They would not overturn Citizens United. They would simply require the same transparency for billion-dollar political operations that the law already requires for a $500 donation to a congressional campaign.
The obstacle is not constitutional. It is political. The lawmakers who could pass disclosure laws are the ones who benefit from the current system.
