Proportionality and the fight against international tax abuse: comparative analysis of judicial review in EU, international, investment and WTO law’

This contribution considers the use of the principle of proportionality to review measures combatting international tax abuse (avoidance and evasion). Our claim is that proportionality, which tends to be viewed as the key analytical tool to balance tax equity against the interests of taxpayers, is ill-suited to the review of such measures. This we will demonstrate from a theoretical angle, but also through the analysis of the CJEU, international investment tribunals and WTO adjudicatory bodies: rather than balancing tax certainty against tax equity or focusing on the efficiency of the anti-tax abuse measures in the pursuit of substantive policy goals (the types of enquires normally associated with proportionality), what we observe is an assessment and gradual demarcation of the rightful territorial extent of the State’s taxation powers.