"During his tenure in the Senate, Specter championed Pennsylvania's economy and took an active interest in foreign affairs, meeting with dozens of world leaders as well as supporting appropriations to fight the global HIV/AIDS pandemic and backing free trade agreements between the U.S. and under-developed countries," according to a bio from the University of Pennsylvania Law School.
He served on the Senate Judiciary Committee, of which he was chairman from 2005 to 2007. He served as chairman of the Senate Select Committee on Intelligence from 1995 to 1997. And he was a senior member of the Senate Appropriations Committee.
Specter brought more financial resources to Pennsylvania than anyone in the state, working with mayors and other local leaders to help them get grants and aid, Madonna said. And he's remembered across the state's 67 counties for his efforts.
"He didn't shy away from pork," Madonna said.
He participated in the confirmation hearings of 14 U.S. Supreme Court nominees, the Penn bio says. He is remembered for leading the charge against conservative nominee Robert Bork and going after Anita Hill, who accused nominee Clarence Thomas of harassment.
"No member of Congress shaped the Supreme Court more than he did," Madonna said. "He had a prosecutorial mindset. He could be incredibly persuasive as an interrogator."
Specter straddled right and left. He criticized Republicans for President Clinton's impeachment and voted in favor of the Iraq war. He supported embroyonic stem cell research.
During the 1990s, he briefly announced a run for president but eventually dropped the effort and endorsed Bob Dole.
Despite his longtime membership in the Republican Party, Specter became more alienated from the party as it grew more conservative.
Like many of his moderate compatriots he came to be viewed by the new conservatives as a RINO -- a Republican in Name Only. Decades after he switched to the Republican Party, he changed his stripes again. He became a Democrat in 2009, saying Republicans had moved too far to the right and embraced social conservatism.
The move gave Democrats a 60-seat filibuster-proof majority in the Senate. Two years later, when he ran for re-election, Specter lost in the Democratic primary, ending his political career.
After the loss, he moved from the halls of Congress to those of academia, taking on a new role at the University of Pennsylvania Law School as an adjunct professor.
"Arlen's knowledge of the inner workings of the government and lawmaking is second to none," said Michael Fitts, the law school's dean. "The insight he brings from his career in public service, particularly as a leader on judicial issues, will be invaluable to our students as they prepare for their own careers in the law."
The senator practiced law when he wasn't in office and authored books throughout his career, including:
-- "Passion for Truth: From Finding JFK's Single Bullet to Questioning Anita Hill to Impeaching Clinton"
-- "Never Give In: Battling Cancer in the Senate"
-- "Life Among the Cannibals: A Political Career, a Tea Party Uprising, and the End of Governing As We Know It"
"For the past quarter-century, he's also been a Zelig-like national figure," the Philadelphia magazine article said, referring to the Woody Allen character from the film of the same name who changed his persona as his surroundings and circumstances changed.
"From his role in sinking Robert Bork's Supreme Court nomination to his cross-examination of Anita Hill, from stem-cell research to the impeachment of Bill Clinton, Specter's greatest talent may be his unique ability to put himself -- somehow, some way -- in the center of the nation's most important debates," the article said.