Jeh Johnson, the general counsel for the U.S. Department of Defense, has announced that he is stepping down at the end of the year after almost four years in the job.

It is anticipated that Johnson, 55, will return as a partner to Paul, Weiss, Rifkind, Wharton & Garrison, the firm where he has spent the bulk of his private legal career.

“We are immensely proud of Jeh’s service to our country, and it is our hope and expectation that, after some much deserved R&R, Jeh will choose to return to our firm,” said Brad Karp, chairman of Paul Weiss.

Johnson will likely remain based in Washington, D.C., for the immediate future.

In a letter yesterday to President Barack Obama, Johnson said he would resign effective midnight Dec. 31, and that, after taking some time off, he would return to private practice.

“Thank you for the opportunity to be part of your campaign, your transition and your administration,” Johnson wrote. “Thank you also for the best clients I will ever have: Robert Gates, Leon Panetta, and the men and women of the U.S. military. I wish you continued success in your second term.”

At the Defense Department, Johnson oversees an army of 10,000 lawyers, including 150 who report to the general counsel’s office. He was confirmed to the post in February 2009.

During his time at the agency, Johnson authored a 266-page report concluding that allowing gays and lesbians to serve in the military would cause few disruptions. That report paved the way for Congress to repeal the “Don’t Ask, Don’t Tell” policy.

Johnson also was instrumental in the Obama administration’s handling of military commission trials at Guantánamo Bay, Cuba, and the determination of legality of U.S. military involvement in Libya.

His annual salary at the Defense Department is about $155,000. Last year, average profits per equity partner at Paul Weiss reached $3 million, according to The American Lawyer, a Law Journal affiliate.

Johnson was the first black partner at Paul Weiss. He was a litigation partner from 1994-1998 and 2001-2008, and an associate from 1984-1989 and 1992-1994. He began as an associate at Sullivan & Cromwell, 1982-1984.

He has left Paul Weiss three times for public service positions, only to return. He was an assistant U.S. attorney in the Southern District, 1989-1991, and general counsel of the U.S. Air Force, 1998-2001.

Born in New York City and raised in Wappingers Falls, N.Y., Johnson graduated from Columbia Law School in 1982 and earned his bachelor’s degree from Morehouse College in 1979.

In a speech at Oxford University last week, Johnson said his job at the Defense Department is “to ensure that everything our military and our Defense Department do is consistent with U.S. and international law. This includes the prior legal review of every military operation that the secretary of defense and the president must approve.”

He said that “it is the U.S. military’s efforts against al-Qaida and associated forces that has demanded most of my time, generated much public legal commentary and presented for us what are perhaps the weightiest legal issues in national security,” he said.

He added that in an unconventional conflict, “we apply conventional legal principles—conventional legal principles found in treaties and customary international law.”

He defended the use of some controversial military practices by the Obama administration.

“Some legal scholars and commentators in our country brand the detention by the military of members of al-Qaida as ‘indefinite detention without charges.’ Some refer to targeted lethal force against known, identified individual members of al-Qaida as ‘extrajudicial killing,’” he said.

Viewed within the context of criminal justice or law enforcement, “these characterizations might be understandable,” he said in the speech. “Viewed within the context of conventional armed conflict—as they should be—capture, detention and lethal force are traditional practices as old as armies.”

Johnson said he is a “student and disciple” of Martin Luther King Jr., “though I became an imperfect one the first time I gave legal approval for the use of military force.”

@|Christine Simmons can be contacted at chsimmons@alm.com. Matthew Huisman, a reporter at The National Law Journal, an affiliate, can be contacted at mhuisman@alm.com.