Hard-core cartels are the most egregious violations of competition law. What are the most appropriate tools to fight them?  In this book, the OECD identifies an increasingly successful  "carrot-and-stick"  approach –  applying stiffer punishment for cartel operators and enhancing programmes aimed at rewarding cartel members who decide to defect and co-operate with the authorities.  This book contributes to the existing knowledge about the extent of cartels' overcharges and other harm  to businesses and consumers worldwide, and sheds light on new and effective "leniency programmes", as well as on optimal sanctions in cartel cases.