Principle of proportionality, which provides that the EU measures must be suitable and necessary to achieve the desired end, and must not impose a burden on the individual that is excessive in relation to the objective sought to be achieved

Principle of mutual recognition of goods, which ensures market access for goods that are not, or are only partly subject to EU harmonisation legislation

Principle of res judicata: a case that has been decided by a court of competent jurisdiction, cannot be subject to re-litigation by the same parties

Principle of subsidiarity, which rules out Union intervention when an issue can be dealt with effectively by Member States themselves at central, regional or local level