Ex Post Reviews: Learning from the Past, or Learning in Real Time?

Ex post reviews of antitrust decisions can be used to ensure accountability of decision-makers, as well as to allow them to learn from the successes and failures of prior interventions in achieving their objectives. But in fast-paced markets, disentangling the effects of past interventions over time would be difficult and any lessons from such interventions may be inapplicable to future cases anyway. A more promising form of ex post review relies on monitoring remedial implementation, to allow f