Born in San Jose, California, Sweigert received an Artium Baccalaureus degree from St. Ignatius College (now the University of San Francisco) in 1921 and a Bachelor of Laws from the St. Ignatius College School of Law (now the University of San Francisco School of Law) in 1923.
He was in private practice in San Francisco, California, from 1923 to 1940, and was a lecturer at the University of San Francisco School of Law from 1925 to 1932.
He was an assistant state attorney general (later chief assistant attorney general) of California from 1940 to 1942, and was then executive secretary to Governor Earl Warren 1943.
[1] On April 23, 1959, Sweigert was nominated by President Dwight D. Eisenhower to a seat on the United States District Court for the Northern District of California vacated by Judge Edward Preston Murphy.
He assumed senior status on November 30, 1973, serving in that capacity until his death on February 16, 1983.