4. This Regulation shall be without prejudice to national rules which, in conformity with Union law, prohibit or sanction unilateral conduct or unfair commercial practices, to the extent that the relevant aspects are not covered by this Regulation. This Regulation shall not affect national civil law, in particular contract law, such as the rules on the validity, formation, effects or termination of a contract, in so far as the national civil law rules are in conformity with Union law, and to the extent that the relevant aspects are not covered by this Regulation.