The fact that an integrated dominant firm deals on more favourable conditions with its affiliated divisions may be abusive within the meaning of Article 102 TFEU. It is not clear when and why this is the case. It has sometimes been suggested that, as a rule, dominant firms are not entitled to favour their own activities over those of rivals. This piece shows that there is no such thing as a non-discrimination rule applying across the board, which, if anything, would run counter to the logic and purpose of competition law. A case-by-case assessment is thus justified. There are compelling reasons to expand to exclusionary discrimination the principles set out in the Guidance Paper 2008 for the assessment of refusals to deal and "margin squeeze" abuses.