Maybe the point was that he'd never practiced law before Ike appointed him.
By the time Ike appointed him, he was long past the practice of law, having been a politician for many years.
However, he got his start in politics as District Attorney of Alameda County. He served three four-year terms, starting in 1925, after which he graduated to California Attorney General in 1938, followed by Governor for three terms. He lost out as Dewey's VP in 1948 (they were ahead in the polls).
In 1953, Eisenhower appointed him Chief Justice.