What Is the Mansfield Rule? Certification, Results, and FTC Scrutiny

The Mansfield Rule is a voluntary certification program, run by the organization Diversity Lab, that asks participating law firms and corporate legal departments to consider at least 30 percent underrepresented candidates when filling leadership roles, making senior hires, and staffing client pitches. It is a consideration standard, not a hiring quota: the threshold applies to who gets looked at, not who gets picked. More than 300 organizations across the United States, Canada, and the United Kingdom have signed on for the 2025–26 certification cycle.¹

Where the Name Comes From

The program is named for Arabella Mansfield, who in 1869 became the first woman formally admitted to practice law in the United States when she passed the Iowa bar exam. The idea itself came out of a winning proposal at Diversity Lab’s 2016 Women in Law Hackathon, and the first certification cycle launched shortly after.¹

The design borrows from the NFL’s Rooney Rule, which requires teams to interview at least two minority or female candidates for head coaching and senior football operations vacancies. The Mansfield Rule applies the same logic to law: widen the pool of people who get considered, and let hiring decisions follow from a broader starting point.

How the 30 Percent Requirement Works

Over a full certification year, a participating law firm must ensure that at least 30 percent of the candidates it considers for covered leadership roles and activities come from underrepresented groups. Those groups are women lawyers, underrepresented racial and ethnic lawyers, LGBTQ+ lawyers, and lawyers with disabilities.¹

Diversity Lab calls this “inclusive sourcing.” The rule operates at the top of the talent funnel. A firm that considers a broad pool and ultimately selects a candidate who is not from an underrepresented group still complies, as long as the pool itself met the 30 percent threshold. A federal court examining the program described it as one that “expressly does not establish any hiring quotas or other illegally discriminatory practices, requiring only that participating law firms consider attorneys from diverse backgrounds for certain positions.”¹

Corporate legal departments participate under a higher bar. Their consideration threshold is 50 percent, which Diversity Lab attributes to the deeper and more diverse talent pools many in-house teams already have.

Which Roles and Decisions Are Covered

Certification covers more than a dozen categories of leadership roles and firm activities. A participating firm tracks consideration across all of them in the aggregate across the year. The main categories include:

Equity partner promotions, the most consequential advancement decision at most firms.
Governance and committee appointments, including management committees, executive committees, and partner nomination committees.
Practice group leader roles, which control work allocation within a practice area.
Senior lateral hiring, meaning partners and senior associates brought in from other firms.
Client pitch teams, where visibility directly drives career advancement. Diversity Lab reports that 94 percent of participating firms now consider broader talent pools when assembling pitch teams.¹

Although the program started with large law firms, it has since expanded to midsize firms, in-house legal departments, and participants in Canada and the United Kingdom.

How a Firm Gets Certified

Certification runs on a year-long cycle. Firms begin by committing to publish job descriptions, promotional criteria, and advancement pathways internally, a step Diversity Lab describes as “writing the unwritten rules.” At firms where partnership criteria have historically been opaque, this transparency step is often the most immediate change.¹

During the year, firms join monthly knowledge-sharing calls with other participants and complete periodic check-ins with Diversity Lab to confirm they are tracking their candidate pools. At the end of the cycle, each firm submits a certification form signed by its managing partner or general counsel documenting its tracking data. Firms that meet the consideration threshold receive standard Mansfield Certification.

Mansfield Certified Plus

Firms that go further and show actual results earn the “Mansfield Certified Plus” designation. This requires submitting data to Diversity Lab showing progress in broadening who actually holds leadership positions, not just who was considered for them. The Plus designation is the practical distinction between firms that met a process standard and firms that produced measurable change.

Whether the Rule Has Produced Results

Diversity Lab tracks outcomes among firms that have completed five or more consecutive cycles, comparing them against non-participating firms of similar size. Between 2017 and 2021, underrepresented racial and ethnic lawyers on executive committees grew at roughly 130 percent at Mansfield firms, compared to about 45 percent at non-Mansfield firms. Female equity partnership grew at 20 percent at Mansfield firms versus 7 percent elsewhere. For underrepresented racial and ethnic equity partners, growth was 41 percent at Mansfield firms compared to 16 percent at firms outside the program.²

Shorter-window data from 2017 to 2019 showed the same pattern. Racial and ethnic diversity on management committees grew by 4.4 percent at Mansfield firms and by only 0.13 percent at non-Mansfield firms. On partner nomination committees, non-Mansfield firms saw diversity decline by about 1 percent while Mansfield firms gained nearly 4 percent.²

These figures are self-reported, and firms that opt into the program may already be more committed to diversity work than firms that do not. The gaps are still large enough that the program appears to be doing more than labeling.

FTC Scrutiny and Current Legal Pressure

On January 30, 2026, FTC Chairman Andrew Ferguson sent warning letters to 42 Mansfield-certified law firms. The letters raised concerns that the certification structure could expose firms to antitrust liability under the Sherman Act and the FTC Act.³

The FTC’s concern has two parts. The agency characterized competing firms’ collective agreement to assemble candidate pools against the same demographic benchmarks as potentially anticompetitive coordination. It also flagged the monthly knowledge-sharing calls, where competing firms exchange information about hiring strategies and, potentially, compensation practices.

The letter states that receiving it “is not intended to suggest that you have engaged in illegal conduct.” It is a warning rather than a finding.³

A January 2025 federal executive order directed agencies to end DEI-related programs, offices, and grant requirements across the federal government and its contractors.⁴ That order addresses government-funded programs rather than private voluntary initiatives like the Mansfield Rule, but it is part of the broader federal climate in which the FTC action arrived.

Diversity Lab maintains that the Mansfield Rule is a lawful inclusion effort that expands consideration without dictating outcomes, and it points to the federal court decision that found the program “fully aligned with anti-discrimination laws.” How that framing holds up against antitrust scrutiny is the open question for firms deciding whether to participate in the next cycle.¹

1
Diversity Lab. Mansfield Certification
2
Diversity Lab. Mansfield Outcomes Show Significant Growth in Diversifying Leadership
3
Federal Trade Commission. Warning Letter – Diversity Lab
4
The White House. Ending Radical And Wasteful Government DEI Programs And Preferencing