Richardson, the namesake for the University of Hawaii's law school, died Monday at a Honolulu hospital of apparent natural causes, said his son, Bill Richardson.
Richardson was chairman of Hawaii's emerging Democratic Party from 1956 to 1962 in its efforts to promote statehood and overturn decades of Republican leadership.
After Hawaii became a state in 1959 and elected John Burns as its first Democratic governor in 1962, Richardson served one term as lieutenant governor, becoming the first person of Hawaiian ancestry to hold that office.
"The former chief justice played an integral role in shaping Hawaii's political and legal landscape," said Gov. Linda Lingle, a Republican.
Nicknamed "CJ" for chief justice, Richardson may best be remembered for helping establish the law school at the University of Hawaii, which later bore his name as the William S. Richardson School of Law when it opened in 1973.
Richardson was born Dec. 22, 1919, in Honolulu to Wilfred Kelelani Richardson and the former Amy Lan Kyau Wung. He earned a business degree at the University of Hawaii and a law degree at the University of Cincinnati.
In his 16 years leading the state Supreme Court, Richardson oversaw judgments ensuring public beach access, expanding Native Hawaiian rights to use private property, and affirming public ownership of water and other natural resources.
Before his legal and political career, Richardson fought in World War II. He enlisted in the Army Air Forces and later served as platoon leader with the 1st Filipino Infantry Regiment in combat operations in Leyte, Philippines.
Sen. Daniel K. Inouye (D-Hawaii) said he and Richardson became friends shortly after he returned from World War II and they began their political careers.
"He worked tirelessly as a champion of all of Hawaii's people," Inouye said. "Bill believed that Hawaii belonged to everyone and fought for the public's right to access and enjoy everything Hawaii has to offer."
Richardson is survived by three children, six grandchildren and two great-grandchildren.