Homeland Security Secretary Jeh Johnson is steeped in the struggle for black civil rights.

His uncle, a Tuskegee Airman, was arrested for trying to integrate an officers club. His grandfather’s 1956 essay about the plight of African Americans in the South was praised by Martin Luther King Jr. Johnson himself attended Morehouse College with Spike Lee and King’s son, and he plotted student marches at the Atlanta home of King’s widow, Coretta Scott King.

Now Johnson, 56, is at the center of another issue with civil rights implications: how to deal with millions of undocumented immigrants, mostly Latino, who are seeking to remain in the country legally.

This week, President Obama announced that he is giving up on Congress and will pursue a remake of the nation’s immigration system on his own. He put Johnson and Attorney General Eric H. Holder Jr. in charge of delivering recommendations on how far he can go under the law.

The issue is one of the most emotional and contentious in Washington. Activists have chained themselves to the White House gates and held a prayer vigil in front of Johnson’s Georgetown home. But Johnson — a lawyer who previously served as the Pentagon’s general counsel — is careful to frame his approach to immigration less as a civil rights matter and more as a legal question.

“It’s a big, contentious, emotional issue, which is also laden with politics,” he said in an interview. “We’re trying to find the best, most workable and most sustainable position under the law.”

Johnson said that he takes a lawyerly approach to immigration and that he took a similar approach to other controversies he dealt with during his time in the Obama administration.

At the Pentagon, Johnson angered social conservatives by helping lead the effort to repeal the “don’t ask, don’t tell” policy banning openly gay troops. But he also riled the antiwar left, which labeled him the “drone lawyer” for his role in expanding the administration’s aggressive drone policies.

Beyond the politics, the urgency of the immigration question was made clear to Johnson during a Mother’s Day tour of a border-control station in McAllen, Tex. The station has been overwhelmed in recent months by tens of thousands of unaccompanied minors from Central America coming across the Mexican border.

“Where’s your mother?” Johnson asked one young girl.

“I don’t have a mother,” she replied tearfully, according to Johnson. “I’m looking for my father in the United States.”

Johnson told a congressional panel that he “returned to Washington the next day determined to do something about this situation.”

A tradition of service

In his office, Johnson has a framed letter from President Franklin D. Roosevelt, thanking his grandfather Charles S. Johnson for serving on a 1936 commission that examined the farm tenancy system.

It is a reminder that public service runs in the family.

Charles Johnson was an influential sociologist who served as president of Fisk University, a historically black college in Nashville. In 1956, he published an essay in the New York Times, “A Southern Negro’s View of the South,” that examined the African American struggle for “full American citizenship.”

Although Southern blacks faced a hostile environment, he wrote, they had not become bitter, hostile or despairing, exhibiting, instead, “something closer to forbearance.” Martin Luther King Jr. sent Charles Johnson a note praising the essay as “the best statement that I have read in this whole area.”

Jeh Johnson — whose name, pronounced “jay,” comes from a Liberian chief his grandfather met on a U.N. mission — grew up in the affluent, mostly white suburb of Wappinger Falls, N.Y.

He would eventually marry a woman who grew up directly across the street, Susan DiMarco, a former dentist, who is white. They have two children and maintain homes in Georgetown and in Montclair, N.J., where Johnson, on weekend getaways, tends to his azaleas and the 200 model trains in a basement evocation of the Northeastern rail system.

Johnson’s father, an architect also named Jeh, served on an urban planning commission for President Lyndon B. Johnson. He urged his son, an underachieving high school student, to consider Morehouse.

At a commencement address at his alma mater in May, the younger Jeh Johnson described his cultural awakening. Johnson, a political science major, had a 1.9 grade-point average as a freshman but finished with straight A’s, inspired, in part, by marches aimed at having King’s birthday declared a Georgia state holiday. The mind-set of the Class of 1979 was reflected in the selection of Nation of Islam leader Louis Farrakhan and Zimbabwean revolutionary Joshua Nkomo as graduation speakers.

“The great struggles of the civil rights movement — the marches, the sit-ins, the freedom rides — were over,” Johnson told the 2014 graduates. “So we were rebels without a cause. We looked for anything to protest or march to.”

Martin Luther King III, whom Johnson calls “Marty,” said in an interview that Johnson “had a very strong commitment, and always has, to history. Understanding the struggles that people went through is very important to him. His own family heritage is significant. He definitely had a strong commitment to ensuring, trying to create, a community where there is justice and fairness.”

Drone policy

Before being sworn in as secretary of homeland security in December, Johnson had virtually no immigration experience. His selection by Obama to replace Janet Napolitano, a former Arizona governor, was interpreted in the news media as a shift of emphasis away from immigration policy toward national security.

At the Pentagon, Johnson had developed a hawkish reputation. The peace group Code Pink protested in advance of his Senate confirmation hearing by projecting the documentary “Killer Drones and Secret Wars” on the brick facade of his Georgetown home.

“It’s fair to say he wanted to prosecute the most effective counterterrorism operations possible under the law,” said Michele Flournoy, undersecretary of defense from 2009 to 2012. “I do not think he was in the business of bending or changing the law to allow us to do some things we shouldn’t be doing. But within the law, he was willing to pursue the terrorism fight very aggressively.”

Johnson’s views on counterterrorism were shaped, in part, by his experience in New York on Sept. 11, 2001, where he was working as the first black partner of the corporate law firm Paul, Weiss. On that morning — it was his birthday — Johnson was in the office when the hijacked planes struck the World Trade Center. Afterward, he wandered the streets wondering how he could make a difference.

The answer came in 2009 when Obama tapped him to serve as the Defense Department’s general counsel. They had met in 2006 at a fundraiser Johnson co-hosted in Montclair for Sen. Robert Menendez (D-N.J.), and Johnson served on Obama’s campaign finance committee in 2008.

Johnson dismisses criticism of his role in drone policy, recalling a newspaper column that described him as advocating targeted lethal force.

“I called the writer and said: ‘I don’t advocate for any military objectives. I’m a lawyer. I establish the legal reins that policymakers and military generals can operate under,’ ” Johnson said. “I can give legal authority for something, but it doesn’t necessarily make it a good idea to do.”

Former defense secretary Leon E. Panetta, who worked with Johnson in 2011 and 2012, called him a “pragmatic” lawyer who was “not just confined to a legal opinion.”

“He understood the legal issues but also understood the policy issues,” Panetta said in an interview. “He didn’t operate in this splendid island way some lawyers do. He understood what the law is and ‘Is there a way to get to our objective and legally accomplish what we want to do?’ ”

‘Don’t ask, don’t tell’

In 2010, then-Defense Secretary Robert M. Gates assigned Johnson and Army Gen. Carter F. Ham to oversee a 10-month review of the military’s “don’t ask, don’t tell” policy. Obama had announced his intention to pursue repeal, but Gates wanted to be sure that the troops were ready.

They undertook a survey of 150,000 troops, military spouses and interest groups, ultimately concluding that 70 percent of service members believed the effect of repeal would be positive, mixed or nonexistent. Their report was released in November 2010, and a month later, Obama signed legislation repealing the policy.

In the interview, Johnson said that he initially viewed the “don’t ask, don’t tell” as a civil rights issue but that eventually he came to see it as the military leadership did: as an “issue of integrity” because troops were forced to lie about who they were.

He allowed, however, that the policy shift “paved the way for a lot of other changes in the law and said he sees a “broader movement and evolution of public sentiment.”

Johnson has taken an ecumenical approach to his immigration review, meeting with advocates for immigrants, anti-immigration groups, local police departments, federal border agents and religious leaders. But he has been drawn into the political crossfire nonetheless.

After returning to Washington from the trip to McAllen, Johnson briefed Obama, who launched an administration-wide response to provide shelter for the Central American children.

Republicans called on Johnson to testify at hearings on Capitol Hill, where they assailed the administration’s immigration policies as weak and ineffective in deterring the child migrants. At the same time, advocates for immigrants said the crisis was further evidence that Obama should act unilaterally to reform the system.

“There is a passage in my grandfather’s article that I will someday quote,” Johnson said, when asked about the emotional response of immigration activists. “He said our situation should not fall into despair; we should never lose hope and always have faith in the democratic process. I think that resonates in a lot of different contexts.”