Brown's college education was interrupted by the draft, but as a Quaker, he had registered as a conscientious objector, and in 1942, he entered the Civilian Public Service at Camp 21 in Wyeth, Oregon.

During his service at Camp 21, Brown realized that he could not change the broader society while he was isolated in Civilian Public Service and rescinded his conscientious objector status in 1944, entering the United States Army, serving in World War II as an instructor and rising to the rank of lieutenant by the time of his discharge in 1946.

Once the war ended, he returned to college, finishing his education at UCLA, where he graduated with a BS degree in Industrial Physics in 1946.

Brown was a strong opponent of the expansion of the conflict and joined a Quaker protest on the steps of the Capitol in 1965, daring police to arrest him with the other anti-war protestors.

The Fiscal Year 1966 Department of Defense Appropriations Bill passed the House of Representatives 392–1, with Brown the sole dissenting vote.

In March 1966, the fiscal year 1966 Supplemental Appropriations Bill with funding for Vietnam passed the House 393–4, with Brown joined by Representatives Burton, Conyers, and Ryan.

In August 1967, Brown was once again the sole dissenting voice against the fiscal year 1968 Defense Appropriations bill, which passed the House 407–1.

Representative John V. Tunney entered the race early and painted himself as a young, charismatic and energetic "Kennedy-esque" candidate, as opposed to the older, established Murphy.

Suddenly young voters flocked to the older Brown, and what seemed like an easy nomination for Tunney turned into a dogfight.

Tunney used a late spending spree on television ads and after a hard-fought nasty campaign, Brown narrowly lost the primary.

Following his defeat by Tunney in the California Senate race, Brown was awarded a Ford Foundation Fellowship and studied for a time with Ivan Illich at his Intercultural Documentation Center at Cuernavaca in Mexico.

Being a progressive Democrat from a largely-Republican area, Brown was famous for running in more close elections than any other representatives in the 20th century without being defeated.

(A close election is considered by most pundits to be 55% of the vote or less, as most incumbent members of Congress easily top 60% in their races.)

In 1980, the Ronald Reagan landslide almost forced him from office, and he struggled to hold on with 52.5% against Republican John Paul Stark.

The 1996 race was even closer, as he barely defeated San Bernardino County Superior Court Judge Linda Wilde with 50.5%, winning by a plurality of only 996 votes.

Brown died on July 15, 1999, at the age of 79 in Bethesda, Maryland, from an infection developed following heart valve replacement surgery in May of that year while he was serving his 18th term in the House.

Such successes and his continuing concern to demonstrate the practical application of advances in science and technology, he instituted the first video conferences in the U.S. Congress between the US and the Soviet Union/Russia, between 1987 and 1990.

In 1992, for example, he led a 60 Minutes investigative team to Central America to expose the use of U.S. taxpayer dollars for the construction of export processing zones in which workers were being grossly mistreated and denied their fundamental human rights as they made apparel and other consumer products exported back to the U.S. His investigation and expose surfaced in the 1992 presidential election campaign and also resulted in the Congress immediately cutting off the use of any taxpayer funds for the development of such export zones (EPZs) anywhere outside of the U.S. Brown's wife was Marta Macias.