Criminalising cartel conduct has become a worldwide trend. Cartels arise when competitors collaborate instead of competing. Cartels that rely on secrecy and deception among their participants with the deliberate aim of avoiding discovery are considered egregious violations of competition law. One possible way to prevent such conduct is through an effective cartel regime.

This thesis analyses the effectiveness of the cartel regime in New Zealand before the introduction of a cartel offence in 2021. It develops a framework according to international standards to measure the effectiveness of civil cartel law and examines the cartel cases from 2004 to 2022 and the work of the competition regulator, the Commerce Commission. It discusses the existing cartel detection measures, the cartel awareness, the Commerce Commission’s powers and its enforcement regime. It also focuses on the path to cartel criminalisation in legal terms by investigating the parliamentary debates and submissions from the public to the Commerce (Cartel and Other Matters) Amendment Bill 2011 and the Commerce (Criminalisation of Cartels) Amendment Bill 2018. The research demonstrates the thesis’ first conclusion that introducing criminalisation might not have been justified in the New Zealand context because the civil regime and the existing methods of detection and deterrence of cartels were satisfactory.

Despite this first conclusion—and given that criminalisation is now part of New Zealand law—the second part of the thesis endeavours to formulate beneficial strategies and practices to help establish an effective (criminal) cartel regime. The United Kingdom's and Australia's first experiences with their criminal cartel regimes offer several lessons to strengthen the New Zealand regulator’s approach to cartel enforcement. Using these two countries as examples is significant because they have had different experiences with criminalisation so far. In the United Kingdom, the criminal cartel offence was considered a failure and led to an immediate law change and the dissolution of the regulator. The Australian Competition and Consumer Commission, on the other hand, was the main driver for criminalisation and managed to win its first criminal cases, albeit through guilty pleas.

Adapting to a dual, civil and criminal, cartel regime certainly poses challenges for regulators. The lessons developed in this research can help overcome technical and strategic challenges. They advise, among other things, to strategically plan investigations and include the prosecutor early in order to come to a satisfactory conclusion. They also acknowledge the leniency regime as crucial but recognise that it should not preclude the collection and evaluation of the evidence by the regulator. Ultimately, public support is vital and should be increased by raising awareness through good use of the regime.