He graduated from the California State Normal School to become a teacher, while also studying law in the offices of future Supreme Court Justice John E. Richards.

In 1907, one year after the aftermath of the San Francisco earthquake, Langdon carried out the successful prosecutions both of Mayor Eugene Schmitz and political machine operator Abe Ruef for bribery and extortion, along with special assistants Francis J. Heney, Hiram Johnson and Matt Sullivan.

[12] In December 1918, Governor William Stephens appointed Langdon presiding judge of the newly minted First District, Second Division, of the California Court of Appeal.

[18] The majority of the court upheld the death penalty, but in dissent Langdon urged the governor to grant executive clemency on the basis of Dias' mental incompetence at the time of the killings.

[18] On April 20, 1908, he married Stanford-trained school teacher Myrtie Conneau McHenry (December 2, 1878 – August 18, 1959), a wealthy widow from Modesto, California.