The imposition of effective cartel sanctions is shaped by the policy of and guidelines from enforcing authorities, such as the European Commission, as well as the Union Courts. The application of the 2006 Guidelines on Fines has been guided by the jurisprudence of the Union Courts. The Courts have in general upheld the fining methodology expressed in the guidelines and have clarified the way it should be applied in specific situations. The fact that the system of setting and reviewing EU competition fines was found lawful adds to the legitimacy of such fines and their enhanced deterrent effect. The aim of authorities and reviewing courts is to impose adequate and deterrent sanctions, while respecting the rights of defence of the undertakings.