Editing Oligopoly (section)

== Oligopolies and competition laws ==
Oligopolies are assumed to be aware of competition laws as well as the repercussions that they could face if caught engaging in anti-competition behaviour. In lieu of explicit communication, firms may be observed as engaging in [[tacit collusion]], which occurs through competitors collectively and implicitly understanding that by jointly raising prices, each competitor can achieve economic profits comparable to those achieved by a monopolist while avoiding breaches of market regulations.<ref name="Green, E. J. 2014">Green, E. J., Marshall, R. C., & Marx, L. M. (2014). Tacit collusion in oligopoly. ''The Oxford handbook of international antitrust economics'', ''2'', 464-497.</ref><ref name=":1" />

=== Policing of anticompetitive behaviour ===
Competition authorities have taken various measures to effectively discover and prosecute oligopolistic and anticompetitive behaviour.<ref name="Harrington, J. E. 2006">Harrington, J. E. (2006). Behavioral screening and the detection of cartels. ''European Competition Law Annual'', 51-68.</ref> The leniency program and screening are currently two popular mechanisms.

==== Leniency programs ====
Leniency programs encourage antitrust firms to be more proactive participants in confessing collusive behaviours by granting them immunity from fines, among other penal reductions.<ref>Harrington, J. (2006). Corporate leniency programs and the role of the antitrust authority in detecting collusion. ''Competition Policy Research Center Discussion Paper, CPDP-18-E''.</ref> Leniency programs have been implemented by countries including the US, Japan and Canada. Nonetheless, leniency programs may be abused, their efficacy has been questioned, and they ultimately allow some colluding firms to experience less harsh penalties.<ref>Marvão, C., & Spagnolo, G. (2015). Pros and Cons of Leniency, Damages and Screens. ''CLPD'', ''1'', 47.</ref> It is currently unknown what the overall effect of leniency programs is.<ref name="ReferenceB">Choi, J. P., & Gerlach, H. Forthcoming. Cartels and Collusion: Economic Theory and Experimental Economics. ''Oxford Handbook on International Antitrust Economics (Oxford University Press, Oxford, England)''.</ref>

'''Screening'''

There are two screening methods that are currently available for competition authorities: structural screening and behavioural screening.<ref name="Harrington, J. E. 2006"/> Structural screening refers to the identification of industry traits or characteristics, such as homogeneous goods, stable demand, less existing participants, which are prone to cartel formation. Behavioural screening is typically implemented when a cartel formation or agreement has already been reached, with authorities subsequently looking into firms' data to determine if price variance is low or experiences significant price changes.<ref name="ReferenceB"/>