Algorithmic Opacity and Exclusion in Antitrust Law

Traditionally evidence of exclusion was available to those injured by it. If a dominant firm refused to deal with a competitor, perhaps denying an important input, or priced predatorily, there was no difficulty in presenting evidence of the conduct at issue. As means of exclusion became subtler, such as with rebate structures, the conduct was less public, but still evidence was typically available. Rebate terms were often incorporated in contracts, for example, and copies could be obtained from customers. Exclusion by online platforms is very different. When a competitor is injured by, say, a disadvantageous position in search results, the cause is often an algorithm whose function is entirely internal to the dominant firm. In such instances, a private plaintiff may not have access to evidence that would allow it to allege satisfactorily, let alone prove, a violation. This brief note sets out the difficulty this issue poses for competition law