Sim was endorsed by Korean Confederation of Trade Unions (KCTU) and ran a campaign focused on labor[33] and social issues.

In July 2017, with Sim's two-year leadership term coming to an end, the party elected sitting National Assembly member Lee Jeong-mi as the new leader over Park Won-suk by 56 to 44.

[36] The incumbent floor leader of the party, Roh Hoe-chan was chosen to head the parliamentary group in the National Assembly.

Roh's death was widely mourned, attracting thousands of mourners and tributes across the South Korean political spectrum.

[37] The party retained Roh's Changwon seat, beating Liberty Korea challenger in the by-election held on 13 April 2019.

A vote was cast in favor of the motion for the arrest of Representative Lee Jae-myung held at the National Assembly.

[50] Major JP politicians, including Jang Hye-young, criticize the DPK,[51] but have a fairly favorable view of the U.S. Democratic Party style of modern liberalism and Joe Biden.

[56] The party is pursuing an alternative form of economic system in which basic standards of living are provided for everyone, equally.

[56] The party also calls for the protection and increase of labor rights, and they promote unionization in the workplace, in order to equalize the power balance between capitalists and workers.

[citation needed] JP most actively supports multiculturalism and anti-racism among major political parties in South Korea.

The progressive Sim Sang-jung stated, "I will not use anti-American, anti-Chinese and anti-Japanese sentiment in politics" in the 2022 South Korean presidential election.

[58] In the midst of the conflict between the United States and China for regional hegemony and Japanese attempts at rearmament, the party believes peace in the Korean peninsula is a paramount issue.

Representatively, there is an online dialogue with Ryu Ho-jeong and Joshua Wong in 2019, and in the same year, JP officially supported the Hong Kong democracy movement in 2019 at the party level.

At the time, the main opposition LKP and the ruling DPK did not reveal the party's position in Hong Kong's pro-democracy movement, fearing excessive friction with China.

JP opposes the "U.S.-led United States, Japan, and South Korea Triangle Alliance" (한미일 삼각 동맹).

[62] Jang Hye-young, the party's main politician, is actively expressing her pro-American diplomatic and cultural views.

[64] JP criticizes the ultra-nationalist project led by the Japanese conservative government, but, unlike DPK, opposes excessive use of anti-Japanese sentiment in economics and diplomacy.

[70][71] On 5 June 2023, members of the Green Party of the United States, including 2020 presidential candidate Howie Hawkins, visited the National Assembly of the Republic of Korea to meet with Justice Party members of parliament Bae Jin-gyo and Sim Sang-jung.

[73] Non-DPK/social-democratic "liberals" such as Sim Sang-jung, Jang Hye-young and Ryu Ho-jeong form the mainstream of the party, and their individual opinion group character is not clear.

In the past, Roh Hoe-chan was also a liberal belonging to the mainstream of the Justice Party before he died of suicide in 2018.

[75] The mainstream of the party has socio-cultural liberal/progressive tendencies, suggesting a differentiated identity from the DPK, but at the same time support moderate economic policies.

Transformation was created through the integration of the party's former leftist groups, 'Network for Equal Society', 'Labour Political Solidarity', 'Democratic Socialists' and 'Momentum'.

[77] Inaugural Remarks at the "Transformation" Launch Ceremony on August 21, 2022[citation needed] "The second act of progressive politics must start based on a clear ideology and route," he said.

[citation needed] "In this position of the Justice Party leadership (voting in favor of the motion for arrest according to the party's theory of abolishing the privilege of non-arrest), there is no awareness of the problem of the Prosecution Republic's arbitrary abuse of the right to investigate and prosecute, and there is no consideration for the people's concerns about it.

However, the response to the Yoon Seok-yeol government's investigation into political elimination, which is moving toward a prosecution republic, cannot be 'live kindly'.

Former party leader Lee Jeong-mi and National Assembly member Bae Jin-gyo [ko] are representative figures.