RALEIGH, NC (Reuters) - In the latest expansion of big law firms' diversity efforts, Arnold & Porter Kaye Scholer and Gibson, Dunn & Crutcher have joined a new initiative aimed at increasing Black equity within their offices, the firms said Wednesday.

The pair are the lone law firms, for now, among an expanded roster of major businesses pursuing Management Leadership for Tomorrow's Black Equity at Work certification, which creates a framework for companies to improve the number of Black employees in leadership, bridge the pay equity gap and develop more inclusive workplaces.

The 2020 inaugural class of 12 employers pursuing the MLT program included top companies like Amazon, PNC and ViacomCBS, but no law firms. The latest class of 12, along with Gibson Dunn and Arnold & Porter, boasts the likes of BlackRock, Cargill, Deloitte, Nike and State Street, MLT said Wednesday.

MLT Founder and CEO John Rice said that he expects more law firms to be among future cohorts seeking certification.

"Law firms are a priority segment for this initiative for a few reasons. Many firms recognize they have a great deal of progress to make before they get to a place of Black equity, and they are committed to doing the necessary work," Rice said.

Lawyers and staff at Arnold & Porter and Gibson Dunn are working on plans that will later be approved by MLT. Once they get the green light, they and other participants have three years to meet their goals to receive the full certification.

Law firms, under pressure from clients and their own lawyers to show progress on racial and gender diversity, have increasingly enrolled in outside certification programs. One of the most popular initiatives is the Mansfield Rule, a certification program run by the Diversity Lab that works to increase representation of women, racial minorities and members of the LGBTQ community in law firms.

Arnold & Porter is currently Mansfield certified, while Gibson Dunn hasn't participated.

Arnold & Porter chairman Richard Alexander said that working toward the additional certification from MLT will allow the firm to focus directly on its Black staff and lawyers.

"The Mansfield and MLT certifications are really accretive to what we're trying to accomplish as a business," Alexander said.

No single team will be responsible for working toward the Black Equity at Work certification at Arnold & Porter, Alexander said. The firm will use the combined efforts of its diversity committee, executives and practice group leaders.

Gibson Dunn's leadership was first inspired to get involved in MLT's program when firm client Amazon started its certification process, said Zakiyyah Salim-Williams, Gibson Dunn's chief diversity officer. Now the firm has an internal group of about a dozen lawyers proactively looking at the firm's diversity pain points.

"I truly think that our clients and our firm have the same goal, which is greater inclusion and greater equity in the legal profession," Salim-Williams said. "Our clients pushing us is a great thing, because we're already pushing ourselves."

In addition to working toward the MLT Black Equity at Work certification, Gibson Dunn in 2019 launched its Black Advancement Initiative to improve the recruitment, retention and career advancement of Black talent within the firm.

Rice said his organization also has plans to launch a MLT Latinx Equity at Work Certification in the near future.