John L. Saltonstall Jr. of Westport Point, formerly a prominent Boston lawyer, civil libertarian, and former member of the Boston City Council, died on April 25 at Charlton Hospital in Fall River after a long illness. He was 91.

Mr. Saltonstall was born in 1916 in Beverly. He graduated from Harvard College in 1938 and Yale Law School in 1941. Mr. Saltonstall volunteered three times for military service during World War II, but he failed the physical exam on each try. Instead he served his country as a member of the War Labor Board, which resolved disputes between workers and management in critical industries where strikes had been outlawed for the duration of the conflict.

After the war, Mr. Saltonstall worked briefly for the American Civil Liberties Union in New York city, and then returned to Massachusetts and joined the now–defunct Boston law firm of Hill&Barlow, where he was a litigation partner for more than 30 years.

During the 1950s, Mr. Saltonstall made a reputation as a defender of freedom of speech by successfully representing Communists who had been arrested for distributing political pamphlets on Boston Common, as well as Leon J. Kamin, a Harvard professor charged with contempt of Congress for refusing to identify fellow Communist party members during the Army–McCarthy hearings.

Mr. Saltonstall’s legal work also preserved Mount Greylock in Berkshire County from commercial development as a ski area. His 1966 Massachusetts Supreme Judicial Court case, Gould v. Greylock Reservation Commission, is a landmark in environmental law that stands for the proposition that state–owned lands are a public trust that cannot be turned over willy–nilly to private developers.

In 1967, Mr. Saltonstall traveled to Jackson, Miss. at considerable personal risk to represent an African–American farmer in a slander case. The farmer had called a local official an Uncle Tom for bowing to segregation in the schools there. In retaliation, a local court had seized the farmer’s property. Mr. Saltonstall persuaded the Mississippi Supreme Court to reverse the judgment on free–speech grounds and return the farm to its rightful owner.

Mr. Saltonstall served two terms on the Boston City Council, from 1968 to 1972. He ran unsuccessfully for mayor against Kevin White and others in 1971. He was the Democratic nominee for Congress in 1958 in a district comprised of Brookline, Newton, and parts of Boston, but lost narrowly to the Republican incumbent, Laurence Curtis.

During the 1960s and 70s, Mr. Saltonstall maintained a law office in Edgartown. He had summer homes in Chilmark and later in West Tisbury. He was town counsel for Gay Head, and in that capacity was instrumental in acquiring Philbin Beach for the town. After retiring from Hill & Barlow, Mr. Saltonstall taught at the McGeorge School of Law in Sacramento, Calif., and later served as a volunteer staff attorney for Legal Services of Cape Cod&the Islands in Hyannis.

Survivors include three children, Stephen, a lawyer, of Sandgate, Vt., Sarah, a registered nurse, of Aquinnah, and Thomas, a human resources executive, of Dennis; two sisters, Jean Hausserman of Cambridge and Anne of Plymouth, N.H. ; a brother, David, of New York city; two grandchildren, Mary Damema Zoss of Lyons, Colo. and Milo D’Antonio of West Tisbury; three great–grandchildren, Marissa, Lucas and Lazlo D’Antonio of West Tisbury; and his companion of many years, Yvonne Barr of Westport Point. Two marriages, to Margaret Bonnell Saltonstall, now deceased, and Adriana Gianturco of Sacramento, Calif., ended in divorce.

A memorial service for Mr. Saltonstall will be held on May 5, at 10:30 a.m. at King’s Chapel on Tremont street in Boston.