South Korea is a robust, multiparty democracy, but this was not always the case. In fact, through the 1980s, South Korea was ruled by a dictator, General Park Chun-Hee, with the support of the Untied States.
All sides of the political spectrum are represented in South Korea, including a fairly robust left, robust enough to maintain a left third party alternative to the liberal and conservative parties. The biggest South Korean left party to date was known as the Democratic Labor Party ("DLP"), which carried 13% of the South Korean vote in the 2004 parliamentary election. But the DLP fell victim to in fighting, and after different iterations, eventually became the Unified Progressive Party ("UPP"), which carried about 6% of the vote in the 2012 election.
In 2013, Representative Lee Seok-gi of the UPP was accused by the government (headed by the conservative Saenuri Party) of plotting to overthrow the South Korean regime based on the contents of a speech that Representative Lee related to North Korean unification. The government accused Lee of violating South Korean's harsh National Security Law, which prohibits a wide variety of speech that the government might consider potentially seditious or sympathetic with North Korea.
Following Representative Lee's arrest, the government then brought dissolution proceedings against the UPP, arguing that the entire political party was a threat to South Korean democracy. The government’s conduct greatly chilled speech in South Korea, with people afraid to speak their minds about either Representative Lee or the UPP. Media outlets like the New York Times and The Guardian called the case “unusual” and a “test of the health of South Korean democracy,” in light of the government’s attempt to use national security laws to repress political dissent.