The recent series of court decisions to reject detentions for suspects in high-profile cases should give the prosecution a lesson.

The Korean prosecution, which is the sole agency with the right to indict, is notorious for seeking to detain the people it accuses. They are even keener on physical detention if the cases are politically sensitive or draw a lot of public attention.

That clearly goes against the spirit of the Constitution, which upholds the principle that people are presumed innocent until proven guilty by the court. Everyone has the right to undergo investigation and stand trial without being detained.

The prosecution ignored the principle again when it arrested former Defense Minister Kim Kwan-jin on suspicion of involvement in the alleged political exploitation of the cyber warfare unit for the past conservative government of Lee Myung-bak.

But Kim was set free through a habeas corpus petition, with the court rejecting prosecutors’ plea to keep him incarcerated. The court made it clear that there was “room for legal dispute” over what he had done and a “need to protect the his right to defense.”

This means the evidence prosecution secured was not sufficient to detain Kim, but it nevertheless stuck to its practice of seeking an arrest warrant for people implicated in prominent cases.

Prosecutors investigating the Kim case also detained former Deputy Defense Minister Lim Kwan-bin for the same charges. Lim filed a habeas corpus petition too, and the court released him, saying that there was room for dispute and that there was little concern he might flee or tamper with evidence.

The prosecution suffered another setback when the court rejected its request for an arrest warrant for Jun Byung-hun, former senior presidential secretary for political affairs.

Jun, a former lawmaker who had been tapped as President Moon Jae-in’s first top political adviser, was implicated in a graft case involving a home shopping company and the Korea e-Sports Association, which he founded and headed until recently. Jun’s three associates working for the association had been arrested on charges of taking money from the home shopping company in return for Jun’s influence.

In Jun’s case too, the court said it saw that the charges filed against him were disputable and that there was a low risk of him fleeing or tampering with evidence.

These three prominent cases provide a clue to what is on the minds of prosecutors: You cannot become a good prosecutor without succeeding in detaining key figures in high-profile cases.

The Kim and Lim case is part of the liberal Moon government’s efforts to dig into what it calls “accumulated wrongs” of the past conservative governments, which have already put tens of former senior officials under criminal investigation.

Some view the investigation into the Jun case -- which deals with suspicions that had been around years ago -- as the prosecution’s tactic to make him a scapegoat for the ongoing campaign against previous governments, which opposition members regard as a political vendetta.

Given what the prosecution has done over the past decades, there are strong grounds for that argument. The prosecution tends to cater to the government in power and abuse its right to indict and seek the detention of those accused to serve its political purposes.

It is not the first time that the prosecution has faced such criticism. That is why the ongoing discussions on reforming the nation’s prosecutorial system, including weakening the prosecution’s power by creating a separate investigation agency to deal with corruption and other crimes of senior government officials, must be hastened.