(Reuters) - The head of the U.S. agency that enforces laws banning workplace discrimination on Monday warned 20 major law firms that their employment policies meant to boost diversity, equity and inclusion may be illegal.

The letters from the U.S. Equal Employment Opportunity Commission's acting chair, Andrea Lucas, seek detailed information on DEI programs at the firms, some of which have ties to President Donald Trump's political opponents or have challenged his policies in court.

Lucas said some of the firms had publicly touted their commitment to diversifying their workforces and at least two had adopted explicit numerical goals for recruiting lawyers based on their race, ethnicity, sexual orientation and gender identity.

Lucas said she was concerned that the firms' policies "may entail unlawful disparate treatment in terms, conditions, and privileges of employment, or unlawful limiting, segregating, and classifying" based on race, sex, and other protected characteristics.

The letters ask the law firms for an array of information about the internships, scholarships and fellowships they offer to law students and their hiring and compensation practices.

Lucas also asked for the name, sex and race of every lawyer who has worked at or applied for a job at the firms since 2019 and whether each one participated in diversity programs or "affinity groups." She asked for some of the information in a "searchable Excel spreadsheet."

Some of the firms that received the letters, including Perkins Coie; Hogan Lovells; Ropes & Gray; and WilmerHale, are representing plaintiffs in current lawsuits against the Trump administration.

A spokesperson for Hogan Lovells said the firm had no immediate comment. The other 19 firms that received the letters did not immediately respond to requests for comment.

Lucas said in a statement that "the EEOC is prepared to root out discrimination anywhere it may rear its head, including in our nation's elite law firms."

The EEOC can investigate companies' employment practices and file lawsuits alleging discrimination, but only after a worker or one of the agency's five commissioners brings a formal complaint. There was no indication that Lucas had filed complaints against any of the law firms.

EXECUTIVE ORDERS

Trump, a Republican, has waged an aggressive campaign to eliminate DEI programs from the federal government, higher education and the private sector. He has also taken several actions against high-profile law firms, alarming many legal experts.

Trump issued executive orders this month targeting Perkins Coie and Paul, Weiss, Rifkind, Wharton & Garrison, citing their allegedly discriminatory internal diversity policies and past work for his political opponents. The orders suspended security clearances for lawyers at the firms and restricted their government access and federal contracting work.

The order involving Perkins Coie also directed Lucas, the acting EEOC chair, to "review the practices of representative large, influential, or industry leading law firms." The commission, like several other federal agencies, was designed to operate independently from the White House.

Perkins Coie filed a lawsuit alleging that the order against it violated its rights under the U.S. Constitution, and a judge in Washington temporarily blocked parts of it last week.

Law school diversity policies have also come under fire from the administration. U.S. Attorney General Pam Bondi has threatened to revoke the American Bar Association's status as the government-designated accreditor of U.S. law schools, citing its requirement that schools provide "full opportunities" for racial minorities and have a diverse student body.

Some major companies have in the past implemented policies to encourage diversity from their outside law firms. The letters from Lucas ask law firms to identify clients that have since 2019 had "diversity requirements" or stated preferences for employee staffing, and the actions the firms have taken to respond to the client requirements, including producing related documents.

Law firms could argue that they cannot turn over certain information on the grounds of attorney-client privilege, and that disclosing some information could expose their clients to investigations by the administration, two legal ethics experts told Reuters.

(Reporting by Daniel Wiessner in Albany, New York; Additional reporting by Mike Scarcella in Washington, D.C., Sara Merken, and David Thomas; Editing by Richard Chang, Alexia Garamfalvi and Richard Chang)