Besides, to prevent corruption suspects from bribing supervisors and getting a clean chit, the names of inspection team members are kept confidential. This makes it almost impossible for the suspects to bribe the inspection team members. These measures have helped prevent inspection team members from falling into the corruption trap.

But Liu's case shows some loopholes are still to be plugged. Had Liu and his team strictly followed the secrecy rule, he would not have been able to amass so much wealth.

Liu's case is, therefore, a wake-up call for the top leadership and the CCDI to strengthen the rules for selecting members of inspection teams and monitoring their activities.

New, strict measures need to be taken. Some scholars propose forming an advisory committee to which inspection teams must submit reports. But the idea is not practical because inspection involves a lot of secretive work which cannot be made public before a case is solved.

A better idea would be to follow the example of the Independent Commission Against Corruption in the Hong Kong Special Administrative Region. The commission has a special L-Group whose members are responsible for supervising their colleagues to make sure they stay clean. Their identities are kept secret, so no one knows who belongs to the special group, but everyone knows someone is watching them. The L-Group helps the ICAC stay clean and powerful enough to fight corruption.

The Chinese mainland could adopt similar measures to keep inspection team members self-disciplined to fight corruption.

Du Zhizhou is a professor at and deputy director of the Center for Integrity Research and Education at Beihang University. This is an excerpt of his interview with China Daily's Zhang Zhouxiang.