From one U.S. attorney general to another, Eric Holder Jr. recently offered Jeff Sessions some leadership advice.

Holder's observations were not solicited.

“On a more personal note, I know you will agree with me that it is the honor of a lifetime to lead the dedicated women and men of the Department of Justice,” Holder wrote to Sessions in a letter in June, which surfaced this week in a Chicago court case against the Trump administration's immigration policies. “They serve the citizens of the United States and pursue justice above all else. They swear an oath to uphold the Constitution; they do not pledge loyalty to any one man, nor any one president. I urge you not to force them to further defend the indefensible—the president's inhumane and unjust executive orders.”

Sessions would surely dispute Holder's characterization of President Donald Trump's executive orders as “inhumane and unjust.” But Sessions has publicly honored the career lawyers and staff at the Justice Department—the thousands of attorneys in Washington and elsewhere who serve year to year, irrespective of the lawyer at the helm on the fifth floor of the Robert F. Kennedy Department of Justice Building.

J. Albert Diaz

“We need to value and support and encourage the fabulous people who work there,” Sessions said in February, at his swearing-in ceremony. “I've worked with them over the years. I know how good they are, and their talents need to be directed at this nation's benefit in a lot of different ways.”

A Justice Department spokesman did not immediately respond to a message seeking comment Friday.

Holder's letter, written on behalf of the California Senate, was attached to an amicus brief California lawmakers filed in support of Chicago, which sued the Justice Department in federal court to block new policies that would withhold grant funding from the nation's so-called sanctuary cities. Some cities and states, rejecting calls from the Justice Department for help in fighting unlawful immigration, have chosen not to actively go into the community to look for undocumented residents.

In his letter to Sessions, Holder urged the attorney general not to “deploy” Justice Department resources “to shut down a prudent and constitutional effort by our clients to prioritize the State of California's limited resources to ensure the health and safety of its residents.”

Covington's participation in the Chicago case—one of several immigration-related lawsuits against the Justice Department—was not a surprise. The California Legislature had contracted with the firm in January—for $25,000 monthly—to craft policy and positions in the face of any adverse action from the Trump administration.

California's state Assembly ended its share of the contract in May. Speaker Anthony Rendon said the house would “continue to seek their guidance as the need arises.” An aide to Senate leader Kevin de Leon said at the time that the upper house had a “number of ongoing projects with Covington,” but did not disclose what they were or who would pay for any continuing services.

Covington offered to submit the brief pro bono and the Legislature accepted, according to the Assembly speaker's office.

Two Covington lawyers in Los Angeles—Daniel Shallman, a partner, and special counsel Mónica Ramírez Almadani—were on the friend-of-the-court brief with Holder. Additionally, Washington-based partner David Zionts and associate Ivano Ventresca were on the filing. Covington teamed with two lawyers from the Chicago firm Arnstein & Lehr—John Gekas and George Apostolides—on the brief.

California lawmakers are considering legislation—dubbed the sanctuary state bill—that would limit state and local law enforcement agencies from spending money to “investigate, interrogate, detain, detect or arrest persons” for suspected immigration violations.

“These various legislative provisions were drafted explicitly to comply with the federal statutory framework for immigration enforcement enacted by Congress,” Covington lawyers wrote on behalf of the Legislature. “But the new immigration conditions imposed unilaterally by the defendant attorney general could call into question both current state statutes and provisions of pending SB 54.”

A team from Wilmer Cutler Pickering Hale and Dorr, including David Ogden, Debo Adegbile and Jamie Gorelick, filed the case for Chicago on Aug. 7. Gorelick is a lead attorney for White House adviser and Trump son-in-law Jared Kushner on ethics matters.

Several major U.S. law firms have sued the Justice Department or the White House on behalf of cities and other groups against immigration policy and diversity of service in the military.

Hogan Lovells and Dechert, representing Philadelphia, brought the latest challenge over sanctuary cities in a suit filed on Wednesday. Covington is counsel in a new lawsuit challenging the Trump administration's move to ban transgender people from serving in the military.