After the war, he joined his brother Adolphus in the Imperial Valley as a farm hand and mule skinner, then, at the age of 26, as a school teacher.

[5][3] During his term, the cities of Wilmington and San Pedro, were merged with the city of Los Angeles, and Shenk later recalled "a midnight trip midst irate farmers and sharp-toothed watch dogs as he hurriedly listing polling places and secured names of election officers for the required ordinance calling the annexation election."

The Outer Harbor was saved for the people of Los Angeles.Barnes added in regard to Shenk's influence: "Then there was the development of municipal power; the "Hyperion" sewer problem; the famous Griffith Park case ... the acquisition of the Los Angeles Public Library site; [and] the Water District Act of 1913—still known as the Shenk Act.

[6] Shenk's decision "that businesses had the right to charge whatever they desired and could change their prices at will,"[7] resulted in unprecedented discrimination against African Americans throughout the city.

[14] In August 1913, Governor Hiram Johnson appointed Shenk to succeed Nathaniel P. Conrey as a judge in the Los Angeles Superior Court.

[16][17] In 1924, Governor Friend W. Richardson named Shenk as an associate justice of the California Supreme Court, where he sat for 35 years and wrote 1,355 opinions.

[18][19] Another notable opinion was his 1948 dissent in the case of Perez v. Sharp, in which the court held by a vote of 4 to 3 that interracial bans on marriage violated the Fourteenth Amendment to the United States Constitution and therefore were illegal in California.

[20] In his dissent, joined by B. Rey Schauer and Homer R. Spence,[21] Shenk wrote: The power of a state to regulate and control the basic social relationship of marriage of its domiciliaries is here challenged and set at nought by a majority order of this court arrived at not by a concurrence of reasons but by the result of four votes supported by divergent concepts not supported by authority and in fact contrary to the decisions in this state and elsewhere.

[22] They had two sons, Samuel Custer and John Wesley Jr.[1] During the last 35 years of his life, he lived in Los Altos, California, where he was active in establishing a union church.