Principle of mutual recognition of products forbids an EU Member State to deny selling in its territory a product that is being lawfully sold in another Member-state, even if it has been produced in accordance with different technical requirements. This principle is applied to all products not covered by harmonized EU regulations (free movement of goods in non-harmonized sectors).
The European Commission website has a indicative list of goods that are covered by the principle of mutual recognition.
The Member State of destination may refuse the marketing of a product only where this is strictly necessary for the protection of, for example, public safety, health or environment and the according Member State should prove this to the business. Regulation 764/2008 sets out the procedure.
Further information on the principle of mutual recognition and guideline documents on its application are available on the website of the European Commission.