He declined, choosing to focus on reform movements where he advocated for democracy, Korean independence and self reliance from foreign intervention, numerous civil rights and universal suffrage.

Thereafter he was appointed to Gyoseokwan Bujeongja (교서관 부정자; 校書館 副正字) and Seungmunwon Gajuseo (승문원 가주서; 承文院假主書).

In 1883 he was appointed to Seungmunwon Bujeongja (승문원 부정자; 承文院 副正字) and Hunryunwon Bubongsa (훈련원 부봉사; 訓鍊院 副奉事).

These reports annoyed powerful conservatives, but it made Jaisohn widely known and respected among like-minded young intellectuals.

By that time, a small but growing number of young intellectuals believed that fundamental reform had to occur or Korea would fall victim to the neighboring imperialist powers of Qing China, Japan, or Russia.

In December 1884, Jaisohn, following Kim Ok-gyun, was involved in the Gapsin Coup, a radical attempt to overturn the old regime and establish equality among people.

Jaisohn and Kim Ok-gyun, Park Yeong-hyo, Yun Chi-ho, Hong Yeong-shik, and others had planned a coup for seven months, from July to December 1884.

In 1886, Jaisohn lived in Norristown, Pennsylvania, and attended the Harry Hillman Academy (Wilkes-Barre, PA) thanks to the help of John Welles Hollenback.

Jaisohn published the Tongnip Sinmun (also called The Independent) to transform the Korean population into an informed citizenry.

[6] He promoted national independence as the principal political ideal and emphasized neutral diplomatic approaches to protect Korea from China, Russia and Japan.

Under the aegis of the Independence Club (독립협회; 獨立協會), Jaisohn organized the All People's Congress, an open public forum to debate over political issues.

After his return, the Korean government ordered the club to disband and arrested 17 leaders, including Rhee Syngman.

In the United States, Jaisohn conducted medical research at the University of Pennsylvania and later became a successful printer in Philadelphia.

When he heard the news of the March 1st Movement (1919), a nationwide protest against Japanese rule in Korea, Jaisohn convened the First Korean Congress, which was held in Philadelphia for three days on April 14–16, 1919.

Floyd W. Tomkins, rector of the Episcopal Church of the Holy Trinity, Philadelphia on Rittenhouse Square and established the "Korean Information Bureau."

In the 1920s, Jaisohn, who had just turned 60, returned to research and spent his 60s and 70s working as a specialist doctor and micro-biologist, as well as occasionally publishing in peer-review academic journals.

[6] Five years later in 1924, Jaisohn went legally bankrupt due to his political engagement and had to resume practicing medicine to make a living.

During World War II, he volunteered as a physical examination officer with the belief that the victory of the U.S. would bring freedom to Korea.

When the date of the first presidential election was confirmed by the United Nations, Jaisohn was petitioned to run for presidency by 3,000 people, including a young Kim Dae-jung, but he refused in the end.

Jaisohn felt that political unity was needed for a new nation, despite his uneasy relationship with the president elect Syngman Rhee.

Suffering a heart attack a week earlier on December 29, Jaisohn died on January 5, 1951, during the Korean War, just two days before his 87th birthday.