Born in San Jose, California, Welsh read law to enter the bar in 1912.

He was in private practice from 1912 to 1932, also serving as a deputy district attorney and a Superior Court judge of Sacramento County, California in 1914.

He was a United States Commissioner for the United States District Court for the Northern District of California from 1914 to 1919.

On June 21, 1939, Welsh was nominated by President Franklin D. Roosevelt to a new seat on the United States District Court for the Northern District of California created by 52 Stat.

This biography of a state judge in California is a stub.