Handbook·Money in politics

Did Citizens United change election outcomes?

Evidence·Verified 2026-07-10

Verdict

Citizens United (2010) and its companion ruling SpeechNow.org v. FEC transformed how much money flows into elections and how much of it is hidden. That part is well documented and essentially undisputed. Whether it changed who wins elections is a genuinely open question in political science. State-legislative studies find real partisan effects tied directly to the ruling. National congressional research finds much weaker and fading effects once diminishing returns and incumbency are accounted for. Judicial elections, with less competing information, show the clearest signs of spending mattering to outcomes. Grade: MODERATE. The honest state of the field is unresolved, not settled in either direction, which is exactly why organized constituent pressure still has room to matter more than money alone in most races.

What the research says

The Court ruled 5-4 that government cannot ban corporations and unions from spending general funds on independent expenditures, while leaving direct-contribution limits and disclosure rules intact.1 SpeechNow.org v. FEC, decided months later, used that reasoning to strike contribution limits on independent-expenditure-only committees, creating the modern Super PAC.2

On money volume, the evidence is strong. Total outside spending rose from $574 million in 2008 to $1.3 billion in 2012 to $3.3 billion in 2020 to roughly $4.5 billion in 2024.34 Super PAC spending grew from $62.6 million in 2010 to over $4.1 billion in 2024.5 Dark money, spending with no donor disclosure, grew from under $5 million in 2006 to $1.9 billion in 2024.6

On outcomes, researchers disagree. Gary Jacobson's long-running work on congressional races found spending helps challengers far more than incumbents, with sharply diminishing returns, a pattern that predates Citizens United.7 A 2024 study modeling all U.S. House races found that while large spending-driven seat swings were once possible, that capacity has faded over the past decade.8 Against this, two separate difference-in-differences studies compared states whose corporate-spending bans were struck down by Citizens United to states with no prior ban and found real Republican gains in state house races, in one estimate averaging about 4 points nationally.910

What it doesn't say

No study proves Citizens United decided any specific national election. The research doesn't support a simple "money bought the outcome" story at the presidential or congressional level, where fundamentals like partisanship and incumbency dominate. It also doesn't support dismissing outcome effects entirely. The state-legislative evidence is peer-reviewed and consistent across two independent teams.910 Effects likely vary by race type, competitiveness, and information environment, and one 2024 study found a negative effect on broader state democratic-performance measures, though that rests on a single study using a composite index rather than direct vote counts.11

What this means for you

Citizens United reliably explains why elections cost more and why donors are harder to trace. It does not reliably explain any single election result. Outside spending appears to matter more in low-turnout, low-information races such as state legislatures and judicial elections than in high-visibility federal races voters already follow closely.12 That's also where an organized, visible constituency has the most room to matter, since those are exactly the races where money currently faces the least competing attention.

How people actually move this

The places where outside money shows the clearest outcome effect, state legislative and judicial races, are also the places with the lowest turnout and the least public attention, which means they're the cheapest venues for organized people to counter organized money.12 The lobbying-strategy literature consistently finds that campaigns combining direct access, testimony, meetings, technical detail, with visible outside pressure, constituent calls, coalitions, local media, report and demonstrate more success than either channel alone, and that persistence across repeated attempts beats a single push. California's SB 79 needed three legislative attempts across eight years, and won only after a coalition paired more than 2,500 targeted constituent calls with an in-person "ditto" testimony strategy that visibly changed who legislators saw as supporters.13

None of the research above says a small group of engaged constituents can outspend a Super PAC. It says spending's power fades fastest in exactly the races, state legislative and judicial, where sustained, coordinated attention has historically had the most room to counter it. The move isn't to match dollars. It's to show up consistently, in person and by name, in the low-visibility races where money currently faces the least resistance, and to treat a single loss as round one rather than the end of the campaign.

Sources

  1. FEC, "Citizens United v. FEC" case page, "Official case summary," 2010. source ↩

  2. FEC, "SpeechNow.org v. FEC" case page, "Official case summary," 2010. source ↩

  3. OpenSecrets, "A decade under Citizens United," FEC outside-spending compilation, 2004-2018, 2020. source ↩

  4. OpenSecrets, 2024 outside spending record, FEC filing compilation, full 2024 cycle, 2024. source ↩

  5. OpenSecrets, "By the Numbers: 15 Years of Citizens United," FEC Super PAC/outside spending compilation, 2010-2024, 2025. source ↩

  6. Brennan Center, "Dark Money Hit a Record High," FEC + Wesleyan Media Project data, 2025. source ↩

  7. Jacobson, "The Effects of Campaign Spending in Congressional Elections," APSR, Regression analysis, decades of follow-up, 1978. source ↩

  8. "Can money buy control of Congress?," PLOS One, "ML estimation, all U.S. House races," 2024. source ↩

  9. Klumpp, Mialon, Williams, Journal of Law and Economics 59(1), "Diff-in-diff, state house elections," 2016. source ↩ ↩2

  10. Abdul-Razzak, Prato, Wolton, Electoral Studies, "Diff-in-diff, state-level spending bans," 2020. source ↩ ↩2

  11. Funk, "Anti-Democratic Influence," Legislative Studies Quarterly 49(3), "Diff-in-diff, state democratic-performance index," 2024. source ↩

  12. Brennan Center, "How Citizens United Threatens Judicial Independence," Judicial election spending tracking, 2023. source ↩ ↩2

  13. California YIMBY, SB 79 campaign coverage, "Named legislative campaign case," 2025. source ↩