The prosecutors’ office is often accused of political bias in its criminal investigations. Such accusations have gained greater credence from recent court decisions on two politically fraught cases.

One case involved Han Myeong-sook, who was prime minister for President Roh Moo-hyun’s administration in 2006-07. The other involved Chung Yeon-ju, who was forced out of the post of president of the Korea Broadcasting System, the country’s most powerful radio and TV network, shortly after President Lee Myung-bak was inaugurated in early 2008.

On Friday, an appellate court upheld a trial court’s decision that cleared Han of taking bribes. Now who should be held accountable?

Prosecutors had charged that Han took $50,000 in bribes from Kwak Young-wook, CEO of Korea Express, in December 2006. But a Seoul district court acquitted her of the charges.

The high court’s action followed the Supreme Court’s decision the previous day to uphold a lower court’s rule on Chung. It said he was not guilty of withdrawing from a winnable lawsuit against the National Tax Service and, by doing so, incurring a loss of 189.2 billion won for the state-run broadcaster.

Shortly after being appointed chairman of the Korea Communications Commission in 2008, Choi See-joong demanded Chung resign as president of KBS ― an act seen by his critics as an attempt to put the network under the Lee administration’s control.

When Chung refused to resign, the prosecutors’ office launched an investigation into an allegation that he agreed to an out-of-court settlement even though the case was winnable. In starting criminal proceedings against him, the office ignored that he had followed the administrative court’s advice that the case be settled through arbitration.

Now Choi is under pressure to resign as chairman of the Korea Communications Commission. Recalling that Choi promised to hold himself accountable if Chung was found not guilty, opposition lawmakers are demanding that he make good on his promise and resign immediately.

He still says he will hold himself accountable. But he refuses to commit himself to tendering his resignation, saying it was not appropriate for the opposition lawmakers to call on him to quit immediately. He says he is pondering many options, including his resignation.

This is nothing but a lame excuse. What better way to take responsibility than to resign immediately?