A week is a long time in politics. Ten days ago, Donald Tsang Yam-kuen still branded it a conspiracy theory when he was accused of accepting undue advantages in connection with his luxurious overseas trips and bargain penthouse deal for retirement across the border. But pressured by an impending ICAC investigation and the threat of an unprecedented impeachment by lawmakers, he finally moved to diffuse the political bombshell over his integrity. He conceded he had learned a painful lesson and initiated a review of the rules governing the conduct of the chief executive and top officials to help restore shattered public trust in him. Tsang's U-turn is probably the most welcome one in recent years. The disclosure that he travelled on the private jets and yachts of tycoons and rented an upmarket Shenzhen penthouse at a bargain price has raised concerns about whether he may have breached the anti-bribery law. He maintained that he has abided by the rules, but conceded that the rules might be insufficient and he may have fallen short of public expectations. It is good that he has the courage to admit his inadequacies and seeks to improve the system. But to many critics, he is shirking his own responsibility and blaming outdated rules. The confession may therefore seem half-hearted and the review no more than a diversion from the issue of whether he breached any law. He is expected to be grilled by lawmakers today when he attends a special Legco meeting. Some lawmakers have vowed to initiate the impeachment mechanism. It is not difficult to see that the current system is inadequate. Unlike civil servants who can turn to the chief executive for guidance when they have doubts about the acceptance of an advantage, the chief executive himself has no approving authority to turn to. The review, to be led by former chief justice Andrew Li Kwok-nang, is to be completed in a few months. It is important that it be a genuine review rather than a knee-jerk response to ease political pressure. Meanwhile, the Independent Commission Against Corruption must look into Tsang's case without fear or favour. Constitutionally, the anti-graft agency is accountable to the chief executive. But that should not prevent it from probing the chief executive if there is a prima facie case to pursue. A clean government is what sets Hong Kong apart from others in the region. The outpouring of public anger shows the people have high expectations about the conduct and integrity of public officials. Any sign of erosion should be guarded against and condemned by the community. Tsang said he had learned a lesson. People will closely monitor whether he lives up to the promise in his final months in office. He should also fully cooperate with ICAC and give a clear account on his conduct.