Optimal dynamic antitrust policies

In a two period model with asymmetric information we study the optimalantitrust policies carried out by a public agency faced with firms'horizontal price-fixing behaviour. We analyse the effect on social welfare in case the Antitrust Authority decides to bind itself to follow the same policy, an investigation procedure, over the two periods. We interpret this policy as the adoption of antitrust guidelines. One can show that the introduction of antitrust guidelines does improve social welfare. Intertemporal dynamic effects on industry's strategies which bring to the ratchet effect do not offset the benefits that accrue to the agency from its commitment to the same policy across the periods.