Old tools for the new economy? Counterfactual causation in foreclosure assessment and choice of remedies on data-driven markets

Abstract Under the Digital Markets Act, gatekeeper platforms abide by numerous ex-ante rules, including narrow data-sharing obligations that address data-driven market tipping. Gatekeepers also remain subject to ex-post competition interventions. While interventions under both ex-ante and ex-post (antitrust) mandates are not novel, they must be approached with extra care in data-driven digital markets, where uncertainty and error costs are high. Therefore, we argue that post-DMA competition enforcement against gatekeepers requires rigorous ex-post economic effects analysis at two levels: foreclosure assessment and devising appropriate remedies. Regarding foreclosure assessment, we propose a ‘multiple-counterfactual-causation-test’ for establishing anticompetitive effects, which should ensure a nuanced analysis of the competitive landscape on data-driven digital markets in the post-DMA world. Regarding remedies, a fine-grained, proportionality-driven assessment of the need for ex-post data-related obligations is vital.