Korea is a democracy, and any one eligible has the constitutional right to seek elected office. But what we hear about some of the candidates running for the April 13 general election provides cause for concern.

Most worrisome is that some of the candidates are former members of a radical leftist party banned by the Constitutional Court for its pro-North Korea, socialist platform and activities that the court said were acts of rebellion.

News reports said that about 40 of the 60 candidates running in the election under the banner of the People’s Union Party are former members of the Unified Progressive Party, which was disbanded by the top court in December 2014. There are about 10 more former UPP members who are running as independents.

The PUP, a coalition of several progressive groups, was launched in February. It is led by former UPP members whose roots are in radical labor and farmers’ groups and its platforms are similar to those of the UPP, except for those found by the court to violate the Constitution.

The real problem is that the PUP candidates include at least 12 former UPP core members who participated in a meeting of its underground sect called “Revolutionary Organization.”

What the RO leaders like former lawmaker Lee Seok-ki said in the meeting, which was recorded by a participant, led to the indictment of Lee and other key UPP members and the disbandment of the party. That they discussed overthrowing the government and destruction of communications and energy facilities in the case of war between the two Koreas shocked many South Koreans.

When the court ruling was handed out, UPP leaders vowed to rebuild their organization in the form of a new party. It is apparent that they have succeeded in fulfilling that promise.

It is certain that there are loopholes in the legal system, as members of a party whose lawmakers forfeited their parliamentary seats because of a court order for disbandment are allowed to seek parliamentary seats.

It makes us shudder to think about the possibility of people like Lee and his comrades and followers taking National Assembly seats again as they did four years ago.

Such a possibility cannot be ruled out completely. In 2014, the UPP earned about 2.2 million votes or 10.3 percent of the total ballots cast to select representatives under the proportional representation system, which gave it six seats.

It is highly unlikely the PUP will get a single constituency seat in the upcoming election, but that should not become a source of relief. There should be greater vigilance against the progressive groups and voters should distinguish the PUP, which, in many regards, is the UPP in camouflage, from other progressive groups like the Justice Party.