Abstract The authors analyse and at the same time criticize the full harmonization principle, with its broad formulation in Article 4 of the Commission proposal for a Directive on consumer rights. It implies a complete, though ''announced'', paradigm shift in EU consumer law from ''minimum'' to ''full harmonization'', while at the same time considerably reducing the protective ambit of prior EC directives against the objectives of Article 153 EC. So far, the proposal seems to be inspired more by the unspecified and unproven belief that the completion of the internal market depends on identical rules in key areas of consumer contract law, such as pre–contractual information, sales law, and unfair terms, while it may only be acceptable in such specific cases as off–the–premises and distance contracts. The paper demonstrates how many open questions will arise the proposal is put onto the EU statute books. These coming controversies will necessarily detract from the original purpose of EU consumer law, namely to increase consumer confidence in the internal market and to give traders a comparable though not identical level playing field, but not to provoke extended litigation about the extent and scope of the full harmonization approach.