In clearing up a situation where corruption is rampant, there is general recognition that at some point an amnesty will have to be granted, but there is much debate over the appropriate timing. If it happens too soon, there is a danger that corrupt officials will just keep their heads low and hope the new campaign will blow over.

Hong Kong got the timing about right: So many police had gone to jail, or were under investigation, that the remainder realized the situation had changed fundamentally. By the time an amnesty was offered, the Independent Commission Against Corruption in Hong Kong, or ICAC, had so much credibility that most took the opportunity to go straight and put their past bad behavior behind them.

But there were two other factors that enabled the city to be successful in its fight against corruption.

One was the overwhelming support of the vast majority of the public. They were absolutely fed up with the brazen misbehavior going on in their midst and threw their weight behind the efforts of the top civil leadership.

The other key factor was the existence of a vibrant free press. News stories about corruption, including photographs of police in uniform collecting bribes in public, helped generate the political will to establish the ICAC in the first place.

The author worked at the ICAC from 1974 to 1980, and for the Hong Kong government until 2008. He is now the search director of Stanton Chase International.