Damage Quantification in Algorithmic Abuse Cases – the Elusive Counterfactual

(by Peter Ormosi) On the 5^th of  February 2024 the Competition Appeal Tribunal published a ruling to determine the carriage dispute in relation to two applications to commence collective proceedings against Amazon regarding Amazon’s Buy Box.[1] Interestingly, the ruling (which went unanimously in favour of Mr Hammond’s application) included a short discussion of the counterfactual.[2] The proposed method for the determining the counterfactual in Mr Hammond’s opt-out class action included re-running Amazon’s original algorithm without the abuse (and logging the resulting outcome as the counterfactual). The CAT seemed sympathetic to this solution. I personally think the proposal in Mr Hammond’s application is a viable approach, and I do believe the CAT must be commended for understanding the novelty of the issue and being open to a method untested in courts. But this ruling draws attention to a much more general question: how to find the counterfactual in a case where the offence is related to conduct by an algorithm?