Corporate sanctions rarely are sufficiently high to be an optimal deterrent against cartels. Sanctions against natural persons can thus complement them. There is no systematic evidence proving the deterrent effects of sanctions on individuals, and/or assessing whether such sanctions can be justified. There is a trend among countries to accept as self-evident that individual sanctions, including imprisonment, can be a useful part of effective anti-cartel enforcement. If a country provides for individual sanctions, a strong argument can be made that relatively short prison sentences are the most cost effective deterrent. However, there are also reasons why countries may provide for longer prison sentences, most importantly that only longer statutory sentences adequately express a society’s condemnation of hard-core cartels. In addition to increasing levels of deterrence, sanctions against individuals can be a powerful incentive for individuals to reveal information about existing cartels and to cooperate in investigations. International law does not recognise the principle of double jeopardy that would prevent authorities in different countries from prosecuting the same person for participation in the same cartel. Nevertheless, where cartels are investigated in a multi-jurisdictional context, jurisdictions may consider arrangements to ensure that only one of them prosecutes an individual.