The court ruling on Saturday to detain former presidential chief of staff Kim Ki-choon and Culture Minister Cho Yoon-sun gave momentum to special prosecutors investigating suspicions they played major roles in blacklisting artists.

Two days earlier, the special counsel team had suffered a setback in their bid to take Samsung Electronics Vice Chairman Lee Jae-yong into custody.

The court refused to detain him, dismissing as unproven their argument that he received special favors from President Park Geun-hye in return for funding her initiatives controlled by her confidante Choi Soon-sil.

In the blacklist case, however, the court accepted their argument for the detention of the two aides to Park. It also worried about the possibility of them tampering with evidence.

Now special prosecutors should step up their efforts to trace the blacklist scandal to its roots. The blacklist could hardly have been made without instructions from the highest power.

The team need to focus their investigation on Park, who is suspected of having ordered Kim to blacklist artists and having received his reports on the lists afterward. The three deny being involved in the blacklist scandal, though Cho admitted to the existence of such lists after persistent grilling at a parliamentary hearing.

A breach of the constitution in connection with the blacklist is likely to become a key charge against Park in her impeachment trial underway at the Constitutional Court.

Representatives of the National Assembly at the trial will reportedly reflect the blacklist scandal in its impeachment charges.

If the special counsel team secures direct or circumstantial evidence that Park ordered the compilation of the lists, it will likely play a decisive role in tipping the scales of the trial toward her removal from office.

Blacklists used by those in political power are a clear violation of democracy and infringement on the constitutionally guaranteed freedom of expression. Such lists are often used as a means to crack down on the opposition unfairly and illegally.

Considering that the court refused to detain Lee on bribery suspicions, the blacklist, for now, seems to be more useful as evidence in the impeachment trial than the circumstantial argument aimed at implicating Park in bribery.

In 2004, when the Constitutional Court overturned the impeachment of President Roh Moo-hyun, it cited as impeachable offenses the suppression on the people and the violation of the basic rights of the people. Park’s instruction to blacklist artists, if proved, will likely be taken as an impeachable act of public suppression.

Special prosecutors are expected to question Park about blacklist suspicions in their planned face-to-face investigation of Park over the Choi peddling-of-power scandal, which led to her being impeached.

The blacklist in question came to light in October last year due to an anonymous tip-off to a local newspaper. Its existence was verified in a recent parliamentary inspection of government offices,

According to the informant, officials of the ministry received the blacklist from the Blue House in May 2015, and acted on the list, namely excluding blacklisted artists from government-sponsored cultural projects or cutting government budgets for them.

The blacklist is thought to have been made between October 2014 and January 2015. Keywords to identify artists to be blacklisted were Moon Jae-in, Park Won-soon and Sewol ferry. Including pro-Moon or pro-Park Won-soon artists in the list in addition to those critical of President Park over the ferry disaster casts a doubt over the Blue House’s intent. Moon is former head of the main opposition Democratic Party who leads polls in presidential race. Park Won-soon is the Seoul mayor and has often clashed with President Park over her policies.

Investigators suspect Kim ordered Cho, then senior presidential secretary for political affairs, to make the blacklists. The lists made by her office were delivered to the ministry through the office of the senior presidential secretary for education and culture.

The arrest of Kim and Cho boosted the special counsel’s investigation into the blacklist scandal, which is expected to support the Assembly’s side in impeachment trial. They should investigate the scandal exhaustively, leaving no doubt whatsoever.