According to the report of OECD, it shows that enforcement of leniency programs by competition law authorities can help to fight hard core cartels, which agreements among competitors to fix prices, restrict output, or divide markets. Since the characteristic of cartel conspiracy meetings might occur in a black room, it is difficult to collect evidence of illegal cartel activities. In order for authorities to detect cartels and also make the ensuing investigations more effective, leniency programs grant reduction in or exemption from sanctions to encourage cartel members which inform evidence about their clandestine meetings and communications.
The U.S. was the first country to introduce a leniency program, while the EU, Germany, South Korea, and Japan have introduced latter. These programs have become more successful in recent years, because the penalties for cartel agreements have increased in some OECD countries. Experience gathered by these authorities to date shows that, the effectiveness of the program would be improved by an increase in the transparency and certainty of the conditions on which any exemption or reduction of fines or surcharges is to be granted.