The death was confirmed by a great-niece, Sharon Welch. The precise cause was not immediately known.
The son of conservative Supreme Court Justice Tom C. Clark, Mr. Clark grew up in the lap of the political establishment and was the last surviving member of Johnson’s cabinet. As a young man, he showed few signs of his firebrand future, but in the half-century that followed his 22-month term as the nation’s top prosecutor, he underwent a remarkable political transformation and became a persistent voice of dissent against the government.
As attorney general, Mr. Clark had prosecuted pediatrician and best-selling author Benjamin Spock for conspiracy to aid draft resisters during the Vietnam War. Within three years of leaving office, Mr. Clark had flown to Hanoi to denounce U.S. aggression and went to court to defend Philip Berrigan and other leading anti-war activists.
For a time, Mr. Clark was a darling of the left — a blunt outspoken former Cabinet member who publicly raised questions about the morality of American interventions abroad. He attacked what he called the United States’ “sham” democracy, ruled not by the people but by the wealthy few, and he decried the nation’s “genocidal” foreign policy and “certifiably insane” military spending.
Still, Mr. Clark continued to serve occasionally in official capacities for the government. In 1979, at the request of President Jimmy Carter, he tried to negotiate the release of 53 Americans taken hostage in Tehran after the fall of the U.S.-backed shah in Iran. When he was denied entry into Iran, Mr. Clark flew home.
Then he returned to Tehran months later to take part in a “Crimes in America” conference that adopted a resolution condemning U.S. actions in Iran. Mr. Clark called the seizure of hostages — who were, at the time, more than 200 days into their incarceration — “understandable” but wrong. He urged the United States to apologize for its wrongdoings in Iran. Carter threatened to prosecute the former attorney general for violating the U.S. ban on travel to Iran.
“If you really love your country, you work very hard to make it right,” Mr. Clark later told the Los Angeles Times. “Anything else is an extreme act of disloyalty and an extreme failure of courage.”
Mr. Clark later sued the U.S. government for bombing Libya in 1986 in response to a terrorist attack on a Berlin disco. He traveled to Panama after the 1989 American invasion to document what he said was the U.S. military’s coverup of a “physical assault of stunning violence,” and he voiced opposition to U.S. war efforts against Iraq in 1990 and 2003.
Conservatives came to loathe Mr. Clark, but support for him also began to erode among left-leaning activists as he made a habit of defending a rogues’ gallery of accused terrorists and war criminals.
“I wish he didn’t do some of these things,” Leslie Cagan, a peace activist, said of Mr. Clark in a 2005 interview with the New York Observer. “He is one of the few public well-known leftists in this country, and it does make our work harder sometimes.”
His client list included political extremist Lyndon LaRouche; several followers of the Branch Davidian cult leader David Koresh; former Black Panther Mumia Abu-Jamal, sentenced to death row for killing a Philadelphia police officer; and Lori Berenson, an American who was imprisoned in Peru for aiding a Marxist revolutionary group.
Mr. Clark also defended Slobodan Milosevic, the former president of former Serbia and Yugoslavia, who died while being tried for genocide by a United Nations tribunal at The Hague; Elizaphan Ntakirutimana, a Rwandan pastor who was found guilty of engineering a massacre of ethnic Tutsis inside his church; and Karl Linnas, an elderly former commander of a Nazi concentration camp.
“You don’t go…