In the first day of the high-profile trial on Tuesday, Justice Minister Hwang Kyo-ahn
made his case against the far-left Unified Progressive Party, while UPP chairwoman Lee Jung-hee spoke up in defense of her party.
The case represents the first time the government has attempted to dissolve a political party.
The cabinet petition to disband the leftist party was filed in early November, a few months after a number of UPP members, including lawmaker Lee Seok-ki, were arrested on charges of plotting an armed revolt against the South Korean government.
Lee and other UPP members are currently standing trial, but are denying the insurrection charges and that they ever even praised North Korean ideology.
Tuesday's trial was focused on whether it is lawful to dissolve the UPP and if so, on what grounds.
The justice ministry called for uprooting the leftist party, saying that the UPP's seeks to install North Korean socialism which violates the basic democratic order of the South Korean Constitution.
It also demanded the court put a temporary stop to the UPP's activities as the party may attempt to subvert the government, as seen in the case of lawmaker Lee Seok-ki.
The UPP rebutted the government's claim that their party is unconstitutional.
It said its style of progressive democracy is aimed at overcoming the ills of capitalism, not following North Korean socialism.
The UPP also claimed that the government is trying to suppress a minor opposition party out of a desire to drive its own political interests.
UPP lawmaker Lee Seok-ki is awaiting a verdict on charges of plotting to overthrow the government.
That verdict is expected to come in February, which observers say is likely to influence the direction of the Constitutional Court's ruling on the UPP dissolution case.
Kim Yeon-ji, Arirang News.