Presumptions in EU competition law

A presumption is usually defined as using a known fact to infer another fact. However, presumptions could be defined more broadly, as including several types of logical leaps, automatisms, burden-shifting mechanisms and predispositions. Using more than 30 such 'presumptions' as examples, this article tries to (i) provide a description and a classification of presumptions in EU competition law; (ii) explore to what extent these presumptions are compatible with fundamental rights and general principles of EU law; (iii) explain the rationales for presumptions in EU competition law; and (iv) draw conclusions for optimal enforcement.