Nicholas deB. Katzenbach. In that post, Mr. Clark was the chief federal government officer present at the Selma-to-Montgomery civil rights march in 1965. That same year he was appointed chairman of a task force that investigated urban unrest after the Watts riots in Los Angeles. He helped draft the landmark Voting Rights Act of 1965.

He was named acting attorney general in October 1966, after Mr. Katzenbach left the Justice Department to be an under secretary of state. He was officially named attorney general the following March.

Melvin Wulf, Mr. Clark’s former law partner, said in an interview with The New York Observer in 2005. He wondered aloud if Mr. Clark’s more recent, controversial actions represented “atonement.”

In 2003, in the magazine Legal Affairs, David McReynolds, a longtime member of the War Resisters League, said he believed that Mr. Clark had been “haunted” by the prosecution of the Boston Five.

Three years after that prosecution, Mr. Clark defended the Harrisburg Seven, antiwar activists led by the Rev. Philip Berrigan, the radical Roman Catholic priest. They were charged with 23 counts of conspiracy, including plotting to kidnap Henry A. Kissinger, then the national security adviser.

The prosecution took five weeks to present its case. Mr. Clark, arguing for the defense this time, took just minutes to make his.

“Your honor, the defendants shall always seek peace,” he said. “They continue to proclaim their innocence. The defense rests.”

The jury deliberated for 59 hours before declaring itself hung. The entire case was later thrown out by a federal appeals court.

Mr. Clark became an office seeker in 1974, when, as a Democrat, he tried to unseat Senator Jacob K. Javits of New York, a Republican. Holding to his principled positions, Mr. Clark often told voters what they did not want to hear. He advocated gun control legislation in speeches to hunters and told defense industry workers that their plants should be closed. He lost convincingly. He ran again for the Senate in 1976 but came in third in the Democratic primary behind Daniel Patrick Moynihan, the nominee, and Representative Bella Abzug.

Mr. Clark was the author or co-author of several books, including “The Fire This Time: U.S. War Crimes in the Gulf” (1992) and “The Torturer in the Mirror” (2010), with Thomas Ehrlich Reifer and Haifa Zangana.

He was also one of the most quotable public figures of his generation, many of his pronouncements tending toward aphorism:

Alex Traub contributed reporting.

View Source