[7][8] Wilbur associated with the firm of Bruson, Wilson & Lamme, and engaged in private practice for eight years in Los Angeles, California.

[19][20] He was especially interested in promoting children's welfare: on the Superior Court, he was presiding judge of the juvenile department;[21][22][23][24] in 1906 he was a director of the Bethlehem Benevolent Board;[25] in 1910, he was a founding director of the Juvenile Improvement Association;[26] in 1912, he was president of the Social Purity League, which offered religious lectures to the public;[27] in 1915, he helped organize the Boy Scouts in Los Angeles, and was named permanent chairman of the executive committee;[28] and he served as president of the state Sunday School Association, organizing evangelical gatherings for young people.

[29][30][31] It was during his time on the California Superior Court that he wrote and first published (in 1905) his popular children's book "The Bear Family at Home, and How the Circus Came to Visit Them".

[citation needed] In 1917, Governor William Stephens appointed Wilbur to the California Supreme Court,[33] where he served as an associate justice from January 1, 1918.

In September 1922, Wilbur defeated William P. Lawlor in the primary election,[34][35] and in November was chosen as the 19th Chief Justice of California, holding the position from January 1923 to March 19, 1924.

[39] The first appointee of President Calvin Coolidge, Wilbur came into the position with a reputation as a man of high intellect and a character of "unimpeachable integrity."

"[40] In July 1925, he accompanied three battleships on a cruise of the Pacific coast, stopping in Marin County for a picnic of 600 midshipmen with a group of more than 100 society women on Mount Tamalpais.

[46][47] Wilbur was nominated by President Herbert Hoover on April 18, 1929, to the United States Court of Appeals for the Ninth Circuit, to a new seat authorized by 45 Stat.

He died of a typhus fever on March 24, 1940, at the age of 33, shortly after having returned from a furlough he spent at the Stanford University School of Medicine, and after having been ill for two weeks.