It took him 48 tries to pass the state bar exam, which he started taking in 1967.
"He strongly believed in justice," said the younger Filer, a Superior Court judge at the Compton courthouse. "He saw that the legal arena was the way that things were getting done."
Filer's life was dominated by civic activism and championing of equal rights for minorities, according to relatives and friends.
A former president of the Compton Branch of the NAACP, he was the flag-bearer for the organization's Southern California delegation to the 1963 March on Washington, at which Martin Luther King Jr. delivered his famous "I Have a Dream" speech. Filer initiated voter-registration drives, promoted peace during the 1965 Watts riots and worked to foster racial harmony, while encouraging talented African Americans to become political leaders.
"His whole persona was so commanding and authoritative that he was indeed a leader," said Doris Davis, who became Compton's first female African American mayor in 1973. "He was a person to whom the community looked for direction on matters of politics and civil rights issues."
Filer's imposing stature — more than 6 feet 3 inches — and his firm handshake belied his humble disposition.
"He was quiet, but vocal when he needed to be, in order to fight for the rights of the people," said Delores Zurita, a longtime neighbor of the Filers and a former Compton council member.
Born June 29, 1930, in Marianna, Ark., to a father who worked as a railway station baggage handler and a mother who taught school, Filer was the youngest of five children, the others girls.
After serving in the Army, he attended what is now the University of Arkansas at Pine Bluff, then studied to be a dental technician at Elkhart Business University in Indiana. While there, he met and married Blondell Burson.
Filer graduated from Elkhart in 1952, and the couple moved to California, settling in Compton. He juggled a variety of jobs, including working as a parking lot attendant and a milk delivery man, and earned a law degree from the now-defunct Van Norman Law School in 1966. A year later he started taking the bar exam.
While attempting to pass the test, he worked as a law clerk and delved into activism. He pushed for equitable representation of African Americans in Compton, led boycotts of banks that refused to hire blacks and participated in efforts to integrate local institutions.
Supporters encouraged Filer to run for a seat on Compton's City Council, and he was elected in 1976.
He served for 15 years, gaining a reputation as a maverick. He didn't hesitate to grill staff and prospective developers about proposed projects or criticize excessive city spending, and his was often the lone voice of dissent.
"This guy was the inquisitor," said Assemblyman Isadore Hall III, who served on the Compton City Council with Filer. "He challenged the intellectual soul of every individual bringing an issue to the council."
Filer finally passed the bar in 1991.
"Perseverance, perseverance, perseverance," he once said of his achievement, which led to his opening a solo law practice. "I was going to take it until the last inch of my breath."
Besides his wife and son Kelvin, Filer is survived by sons Duane, Anthony and Dennis; daughters Maxine McFarland, Stephanie Hoxey and Tracy Filer; 14 grandchildren; four great-grandchildren; and three sisters.
A memorial service will held at 11 a.m. Saturday at the Love and Unity Christian Fellowship, 1840 S. Wilmington Ave., Compton. Filer will be buried in the city's Angeles Abbey Memorial Park.