Cohen supported labor unions, collective bargaining, racial integration, desegregation, and equal opportunity since the late 1930s.
He opposed waste incineration within the city, successfully in the case of a proposed plant near the Philadelphia Naval Yard.
He claimed that these curtailments in waste facility operations produced a saving of $1.5 billion in trash disposal costs over thirty years and enhanced the attractiveness of the city areas of South Philadelphia, Northern Liberties, and Roxborough as targets for development.
In 1995, Cohen declared himself "a Franklin D. Roosevelt Democrat", and thereafter refused any other public comment on supporting political alliances in the city.
At his death in 2005 at age 90, Cohen was one of the oldest American elected leaders in office, serving at large[1] on the City Council.
Elected a delegate to the 1968 Democratic National Convention, Cohen supported the Presidential campaigns of Robert F. Kennedy and Eugene McCarthy, and frequently spoke at rallies opposing the War in Vietnam.
[citation needed] Cohen remained active in Philadelphia politics and civic life, campaigning for George McGovern, running unsuccessfully for the Democratic nomination for City Controller in 1973 and for Councilman at large in 1975.
[citation needed] Cohen's 25 years as at large councilman were the longest tenure in that position since it was created by City Charter amendment in 1951.
Throughout it, Cohen was an independent voice in City Council, actively examining and often seeking to modify or defeat the proposals of Mayors William J.
[citation needed] Over 500 people attended a "Tribute to Change" reception at the University of Pennsylvania, held to raise money to fund Bread and Roses, a Philadelphia charitable foundation, and to honor him and his wife Florence Cohen for their lifetimes of activism, on September 12, 2005.
The event, held near the law school where he had graduated first in his class more than 68 years earlier, turned out to be his last public appearance before his death.
[citation needed] His son Denis P. Cohen served for 24 years as an assistant district attorney, and was a leader of the Philadelphia Bar Association.
His daughter Sherrie Cohen was a trial lawyer in Florida and Philadelphia, as well as an activist for public, political, and gay causes.
[citation needed] David Cohen died on October 3, 2005, at the age of 90, after a hospitalization at Albert Einstein Medical Center, a few blocks from his home of 53 years.