He stood up for women, for workers, for the environment. He joined the Freedom Riders in the 1960s, opposed the Vietnam war in the ’70s, and was arrested while protesting South African apartheid in the ’80s. A national wildlife refuge bears his name.

A champion of civil and constitutional rights during his three decades on Capitol Hill, former U.S. Rep. Don Edwards was known to many as “the conscience of Congress.”

At the age of 100, he died shortly before 9 p.m. on Thursday at his home in Carmel, according to his son, retired Santa Clara County Superior Court Judge Len Edwards.

“He died peacefully and with a great deal of grace,” Len Edwards said. “He died as he lived, an elegant man.”

Edwards had been in declining health for years, and had trouble with his vision and hearing, but he still kept sharp well into his 90s. He had the New York Times read to him every day and kept in touch with friends and politicians, including his former staffer and successor, U.S. Rep. Zoe Lofgren, D-San Jose.

“People didn’t always agree with him, but they respected him,” Lofgren said. “They knew he had integrity and was doing what he thought was right.”

Before Edwards’ 1995 retirement, the New York Times wrote that during his tenure, “a time span that stretches from John F. Kennedy to Bill Clinton, he prodded his colleagues into decisions that did at least as much as any Attorney General to protect people against discrimination.”

Edwards was raised in a Republican family that owned a land title business in San Jose — a place that was far more conservative than it is now — but he proudly considered himself a liberal Democrat.

It was his “gentlemanliness, his civility,” that enabled him to pursue a strong liberal agenda and remain in office for 32 years, said San Jose State political science professor emeritus Terry Christensen. “Eventually, the constituents caught up with Don’s politics.”

It helped him earn the respect of his Republican colleagues, who joined him in landmark bipartisan legislation, including the passage of the Voting Rights Act extension of 1982, the American with Disabilities Act in 1990 and the Civil Rights Act of 1991, passed in response to court decisions to bolster employees’ rights in discrimination lawsuits.

On the environment, Edwards wrote the bill that President Richard Nixon signed in 1972 establishing the San Francisco Bay National Wildlife Refuge. In setting up the first urban national wildlife refuge in the United States, the law preserved a broad expanse of South Bay wetlands, for fish, wildlife and public recreation — blocking the type of development that had filled in large sections of San Francisco Bay in prior decades. Congress renamed the 30,000-acre refuge for Edwards in 1995, and he remained a hero to Bay Area environmentalists.

“Back then the bay was something to use — for sewer outfalls, garbage dumps, anything you didn’t want you put in the bay,” said Florence LaRiviere, a longtime Palo Alto environmentalist who worked with Edwards in the early 1970s to create the refuge. “He listened to us. Without Mr. Edwards, there would be development right up to the edge of the bay. All of the wonderful wildlife would be gone.”

His family said the permanent protection for the South Bay shoreline was something Edwards remained proud of, long after his retirement.

“It’s an open area for families to enjoy and for our environment to be saved that will last forever,” Len Edwards said. “That to me is the most wonderful gift he could give.”

As chairman of the Judiciary Committee’s subcommittee on Civil and Constitutional Rights, Edwards blocked efforts to ban flag burning believing that doing so would hinder freedom of speech rights.

All the hot-button freedom of speech issues came through that committee, said Len Edwards, a longtime juvenile court judge, “and he stonewalled them — flag burning, school prayer.”

He worked for women’s rights and was considered “the Father of the Equal Rights Amendment” that failed to pass in 1971.

“Although it didn’t become part of the Constitution,” Lofgren said, “the effort that surrounded its attempted passage played a large role in facilitating rights for women.”

Born in San Jose in 1915, William Donlon Edwards graduated from San Jose High School, earned a bachelor’s degree from Stanford and spent two years in its law school before becoming an FBI agent in 1940. During World War II, he served as an officer in the Navy, then followed his grandfather and father into the land title business. He joined his father as executive vice president of Abstract & Title.

It didn’t last long. Edwards had married Nancy Dyer in 1938 and they had three sons, but his romance with Clyda Guggenberger ended his first marriage, and damaged his relationship with his father and his family. Divorce was not acceptable to Christian Scientists, and the elder Edwards fired his son. Valley Title Co. resulted, when Edwards and his new wife set up shop in Palo Alto during the 1950s.

For a brief period, Edwards joined the California Young Republicans and became president but resigned when he showed his liberal bent as chairman of the United World Federalists, a group that wanted Red China admitted to the United Nations in an attempt to control the spread of atomic weapons. He didn’t find that inconsistent, noting that Earl Warren, a Republican, was one of the great liberal chief justices of the United States.

He was elected to office by a slim margin in 1962, when his district stretched to Alameda County. He soon established himself as one of the most consistent liberals in Congress — 100 percent favorable voting record in the view of the Americans for Democratic Action, the same by labor’s AFL-CIO. He served as chairman of the California Democratic delegation for 13 years.

As a freshman Congressman, he and two fellow Democratic colleagues traveled to Mississippi in 1964 to join his son, Len, who was helping register black voters. He came alone several months later.

“It’s very touchy when congressmen go to someone else’s district, but in a second trip down there in late July, he came down alone,” Len Edwards said. “It was one of the best times we ever had in our lives.”

The two traveled around the state, stopping to “meet and talk with people about what was happening and what could be done,” he said. “In Sunflower County, where I was living with my friends, he made a statement that if they weren’t being well represented in Congress, he would represent them. It was quite a remarkable display at that time. He’s a hero in Sunflower County.”

Twenty years later, when he was arrested outside the South African embassy while protesting apartheid, he told reporters that President Ronald Reagan’s policy of making change through negotiation and diplomacy wasn’t working. “You have to play hardball,” he said in December 1984. “You have to fight back.”

Perhaps no stand more typified the liberal life of Don Edwards than his opposition to the war in Vietnam. His stand had resulted in the only re-election contest that was close to a challenge during his 16 terms in Congress.

Also in 1975, Edwards was successful in disbanding the controversial House Un-American Activities Committee, which blacklisted communist sympathizers.

“It is the irresistible impulse of government to assume more power,” he told the Mercury News in a 1994 interview. “My role has been to say no.”

Edwards married for a third time in 1981. Edith Wilkie, an administrative assistant to Rep. Pete Stark and an arms control expert, had known and worked with Edwards for several years. They spent summers in Maryland and much of the year in Carmel, after the congressman retired in 1994. She died in 2011.

“He had a tremendous sense of fair play,” Lofgren said. “That could be seen in everything from standing up for free speech rights, religious liberties of others and to be fair to the people who worked for him.”

She remembers when she was an aide to Edwards, Congress would routinely fire all the food service workers on Capitol Hill as a quick fix to budget issues. The mostly African-American workers would appeal to Edwards — even though he wasn’t on the committee that dealt with the issue.

“Standing up for the little guy,” she said, “is what he wanted.”

Staff writers Paul Rogers and Mark Gomez contributed to this report. Contact Julia Prodis Sulek at 408-278-3409.