Anthony Lewis, an indefatigable champion of civil liberties who became known during his half-century with the New York Times as one of the most trenchant legal journalists of his generation and was twice a recipient of the Pulitzer Prize, died March 25 at his home in Cambridge, Mass. He was two days shy of his 86th birthday.

He had complications from renal and heart failure, said his daughter Mia Lewis.

By the time he retired in 2001, Mr. Lewis was widely recognized as the dean of liberal American columnists and had written a book that is regarded as the seminal account of the landmark U.S. Supreme Court case Gideon v. Wainwright.

As a Times columnist for 32 years, he wrote his most noted work on First Amendment rights and the American justice system. In a crowded field of columnists, many of whom were at times enticed to bloviate, Mr. Lewis distinguished himself with the consistent lucidity of his writing and his reportorial approach to the job.

He received his first Pulitzer for national reporting in 1955, at age 28, while working for the now-defunct Washington Daily News. The award recognized his series of articles that cleared a Navy Department employee who was fired for alleged security risks during the Red Scare stoked by then-Sen. Joseph McCarthy (R-Wis.).

Anthony Lewis, shown in 1963 after he won the Pulitzer Prize for coverage of the Supreme Court. (Associated Press)

“Mr. Lewis received the full support of his newspaper in championing an American citizen . . . against an unjust act by a government department,” the Pulitzer citation read. “This is in the best tradition of American journalism.”

In 1963, by then a reporter for the Times, Mr. Lewis received his second Pulitzer, also for national reporting. The citation praised his coverage of the U.S. Supreme Court, and in particular Baker v. Carr, the history-making decision that underlies the “one person, one vote” doctrine in electoral redistricting.

Taken together, the Pulitzers reflect the two most salient themes of Mr. Lewis’s career: a self-professed affinity for the underdog and seemingly infallible command of the law, despite his limited formal training in the field. “I was probably made to be a lawyer,” he once said. “It just didn’t turn out that way.”

Mr. Lewis covered the Supreme Court for the Times for most of the Warren court years, which lasted from 1953 until 1969 and which was credited with handing down some of the most influential decisions of the latter 20th century. Mr. Lewis filled pages of newsprint with analysis of the court’s rulings days or hours after they emerged from the shrouded chambers.

One of those decisions was Gideon, the 1963 case in which the high court established an indigent criminal defendant’s right to legal counsel. Besides his newspaper reportage, Mr. Lewis wrote a book about the case, “Gideon’s Trumpet” (1964), that remains a mainstay of law school curricula. In a 1980 movie based on the book, Henry Fonda played the case’s namesake, Clarence Earl Gideon.

He was a “gambler, drifter and ex-convict,” Mr. Lewis wrote in a quintessential column upon Gideon’s death in 1972.

“Gideon must have seemed the most obscure of patients: a gaunt figure, cast aside by life, without money or influence,” Mr. Lewis continued. “Understandably, it was a death that went almost without notice. But Clarence Earl Gideon was not really so obscure or unimportant. For in his life he had, in a matter of speaking, changed the Constitution of the United States.”

Mr. Lewis covered New York Times Co. v. Sullivan, the 1964 decision that limited the circumstances in which public officials can sue for libel. Mr. Lewis later wrote the book “Make No Law: The Sullivan Case and the First Amendment.” It, too, has found a place in the law school canon.

Mr. Lewis began his column, variously called “At Home Abroad” or “Abroad at Home,” in 1969. He delved into matters including freedom of speech, freedom of the press, immigrant rights, apartheid in South Africa and the Arab-Israeli conflict. Some of his final commentary examined the legal quandaries presented by the terrorist attacks of Sept. 11, 2001, and the First Amendment as it relates to reporters and their sources.

Mr. Lewis said that he drew two conclusions from his decades of work.

“One is that certainty is the enemy of decency and humanity in people who are sure they are right,” he told the Times upon his retirement. “And secondly that for this country at least, given the kind of obstreperous, populous, diverse country we are, law is the absolute essential. And when governments short-cut the law, it’s extremely dangerous.”

Joseph Anthony Lewis was born March 27, 1927, in New York City, and went by Anthony from birth. His father was a textile executive; his mother, he said, dabbled in playwriting.

Mr. Lewis attended the private Horace Mann School in New York, where he edited the school newspaper and where one of his classmates was Roy Cohn, the future counsel to McCarthy’s Communist investigations.

Another friend from his youth was future journalist and author Stanley Karnow, who died in January. They traveled to Europe together during a hiatus from their education at Harvard University, where Mr. Lewis was a top editor of the Crimson and where he received a bachelor’s degree in English in 1948.

Mr. Lewis described himself as “a conservative young person.” He told the Times that he became interested in First Amendment rights through his profession.

“As a journalist,” he said in 2007, “I saw again and again how much we need free criticism of government to keep it honest.”

He joined the reporting staff of the Times right out of college — he had started during college as a copy boy — but was fired after four years. It was a “polite” dismissal, he once told the Boston Globe, and he went off to seek more experience.

He worked for the Democratic National Committee and on Adlai Stevenson’s unsuccessful 1952 presidential campaign before being hired by the Washington Daily News that year as a general assignment reporter. He was at an interview for a job with the Times when someone informed him that he had received the Pulitzer Prize.

He spent a year at Harvard as a recipient of the prestigious Nieman fellowship for journalists, readying himself academically to cover the court for the Times.

“There are not two members of the court itself who could get the gist of each decision so accurately in so few words,” Justice Felix Frankfurter once said about the writer’s court reporting.

The Globe reported that in 1964 Mr. Lewis was passed over for the job of the Times’s Washington bureau chief in part because he had developed too close a relationship with then-U.S. Attorney General Robert F. Kennedy. The job instead went to Tom Wicker, who died last November.

Mr. Lewis became London bureau chief. He wrote, among other articles, the obituary for Winston Churchill in 1965. “Sir Winston Churchill is dead,” he began. “The great figure who embodied man’s will to resist tyranny passed into history this morning.”

Mr. Lewis also reported from Vietnam during that time and continued writing about the conflict as a columnist. In a 1972 piece about U.S. bombing in Vietnam, he called the United States “the most dangerous and destructive power on earth.”

Henry Kissinger, secretary of state and national security adviser under President Richard M. Nixon, was reported to have said of Mr. Lewis that “he’s always wrong.”

“Probably because I wrote in a very uncomplimentary way about him,” Mr. Lewis responded in a 2007 interview with the Times. “He did things that were very damaging to human beings.”

Mr. Lewis taught for many years at Harvard and Columbia University. His books included “Portrait of a Decade” (1964), about the civil rights movement, and “Freedom for the Thought That We Hate: A Biography of the First Amendment” (2007).

His first marriage, to the former Linda Rannells, ended in divorce. Survivors include his wife of 28 years, Margaret H. Marshall of Cambridge, a former chief justice of the Massachusetts Supreme Judicial Court; three children from his first marriage, Eliza Lewis of Newton Centre, Mass., David Lewis of Atlanta and Mia Lewis of Columbus, Ohio; and seven grandchildren.

In his exit interview with the Times, Mr. Lewis remarked that, after witnessing the atrocities of the 20th century, he had “lost my faith in the idea of progress.” But, he added, he was “not willing to give up on rationality.”

“Look, why have I been writing columns rather than jumping off the George Washington Bridge?” he said. “I believe it’s worth appealing to reason.”