Ex-officio cartel investigations and the use of screens to detect cartels


Fighting cartels remains a top priority for competition authorities since cartels are secretive in nature and cartelists take good care in concealing their illegal activities.

Cartel enforcement can therefore be extremely challenging for competition authorities who most of the times can only react after receiving complaints by competitors and customers or applications by participants to a cartel for leniency or amnesty.

More rarely, competition authorities take proactive actions to identify firms which are potentially involved in a cartel conspiracy, or markets which may be affected by cartelisation. These proactive cartel detection tools involve the analysis of observable economic data and firm behaviour, systematic monitoring of media, tracking of firms & individuals to detect behaviour which is inconsistent with a healthy competitive process. Discussing the balance between proactive and reactive detection and particular detection methods may benefit competition authorities evaluating their anti-cartel detection and enforcement policies. 

The OECD Competition Committee discussed Ex officio cartel investigations and the use of screens to detect cartels in October 2013 so as to explore the various screening methods used by agencies and their successful experiences with the implementation of such screens in case enforcement. 



Full set of documents (pdf) including an executive summary with key findings, the background note, expert papers, over 25 contributions from participants and a detailed summary of the discussion. 

Key papers and presentations

Background Note by the Secretariat 
English | Français 

Rosa Abrantes-Metz
US Global Economics Group Paper | PPT

David Gilo
Israel Antitrust Authority PPT

William Kovacic
George Washington University Paper | PPT

Maarten Pieter Schinkel
University of Amsterdam Paper | PPT


Key conclusions from the discussion included: 


Amnesty and leniency programmes continue to be the most effective cartel detection measure. Competition authorities rely on them to detect and investigate cartels and recognise they have a successful detection rate while providing strong evidence on the existence and functioning of cartels.


‌‌Over-relying on such programmes may undermine their very effectiveness. A combination of pro-active and reactive detection tools is still the best option.

‌Among pro-active tools, cartel screening stands out in some cases. Two type of screening approaches exist – an structural approach (analysing what structure/product characteristics in a given industry/market are more prone to collusions) and a behavioural approach (identifying the behaviour/ market outcome of firms resulting from collusive strategies). 

‌‌‌The discussion also concluded that implementing sophisticated screening techniques can be challenging, but competition authorities should consider them especially in situations where they can be most effective. This is the case of markets where data are available (financial markets or procurement markets).

‌‌Other pro-active tools, such as market studies, media monitoring and advocacy with the business community have also resulted effective in detecting cartels and in increasing incentive of firms to enter into amnesty and leniency programmes.


See other Best Practice Roundtables on Competition Policy.




Cartels page

Improving International Co-operation in Cartel Investigations, 2012 (pdf)

Crisis Cartels, 2011 (pdf)

Prosecuting Cartels Without Direct Evidence of Agreement, 2006 (pdf)

OECD Recommendation concerning Effective Action against Hard Core Cartels (1998)

All Competition Policy Roundtables

Competition Home Page 




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