- Most major rules are not challenged in court. To be exact, only 23% of the major rules in our dataset ended up in court, meaning the vast majority of major rules go unchallenged. But the challenge rate has risen over time. As a result, federal courts are resolving many more challenges to major rules than they once did.
- Some agencies’ major rules landed in court more frequently than others. The 78% challenge rate for the Environmental Protection Agency (EPA) was a notable outlier.
- Our study finds lower overall agency win rates than most other studies. Previous studies typically found agency win rates of around 60–70%, with most studies closer to the top of that range. In contrast, our study finds an overall agency win rate of 48% (by major rules) and 57% (by controlling opinions). This discrepancy likely stems from multiple factors. We grouped mixed results with losses in the calculation of our overall win rate (we also present such mixed results side-by-side with outright wins and losses for context). Other studies also covered earlier timespans; for example, none included the Trump or Biden Administrations. Given our study’s consistent unit of analysis and timespan, it is likely that declining agency win rates over time (and, relatedly, the much lower win rates during the Trump and Biden Administrations, as compared to earlier administrations) at least partly explains why we found lower overall agency win rates than earlier studies. Readers should keep these nuances in mind.
- The continuous two-term presidents in our study (Clinton, W. Bush, and Obama) had higher win rates for major rules issued in their second term. Our study does not reveal the cause of such fluctuations, but they should be kept in mind when comparing agency win rates across administrations and when analyzing data from studies that captured opinions addressing agency actions from a particular presidential term.
- Win rates varied widely across agencies. Among the top 10 rule-issuing agencies, the Federal Communications Commission (FCC) had the highest win rate at 72%. EPA and the Securities and Exchange Commission (SEC) had the lowest win rates at 36% and 35%, respectively. But EPA also had the highest rate of mixed results. Weighing those mixed results changes the picture for EPA, especially if one includes mixed results that led only to a remand without vacatur. Taking that approach, EPA’s win rate rises to 62%.
- Our study finds that independent agencies (as defined under 44 U.S.C. § 3502) had higher win rates than executive agencies (54% versus 46%). Agencies led by multimember commissions similarly had higher win rates than single-headed agencies (53% versus 46%).
- While around half of all challenges to major rules were filed in either the U.S. District Court for the District of Columbia or the U.S. Court of Appeals for the D.C. Circuit, these two courts’ preeminence declined over time. The decline for the two courts, dropped from 64% for challenges to the Clinton Administration’s major rules to 62% (W. Bush), 51% (Obama), 35% (Trump), and 22% (Biden).
- Partisan trends in our study paint a mixed picture. Republican administrations generally fared better in front of judges appointed by Republican presidents and vice versa, but Democratic administrations fared considerably better in front of mixed panel majorities than Republican administrations (72% versus 48%).
- Many challenges to the Biden Administration’s rules remain pending. But our analysis of the datapoints through February 2025 finds that the challenge rate to the Biden Administration’s major rules is more in line with the Trump Administration than earlier Administrations. As is the Biden Administration’s win rate: 41% by major rules and 45% by controlling opinions.
- Where a case is filed seems to matter: We also completed an analysis of circuit-by-circuit win rates. We found that, along with the decline of the D.C. Circuit, litigants have been steering cases towards particular courts they view as likely to provide favorable outcomes. And we in fact found differences in outcomes among courts. Most notably, during the Biden Administration, 40% of challenges were filed in the Fifth Circuit courts, of which the Biden Administration won only 21%. Excluding the Fifth Circuit cases, the Biden Administration’s overall win rate increases by 23 percentage points, from 45% to 68%. A similar exercise for the first Trump Administration (excluding the Second and Ninth Circuit) increases the first Trump Administration’s win rate by 8 percentage points, from 46% to 54%.