JTA - Jack Greenberg, a prominent lawyer in the U.S. civil rights movement who once defended the Rev. Martin Luther King Jr., has died.

Greenberg had been suffering from Parkinson’s disease, said his wife, Deborah Cole Greenberg, according to The New York Times. He died Wednesday in Manhattan at 91.

The son of Jewish parents from Poland and Romania who immigrated to the U.S., Greenberg was a pioneer in the civil rights movement of the 1960s and 70s who fought for equal rights for disenfranchised African-Americans.