1. The Union shall comprise a customs union which shall cover all trade in goods and which shall involve the prohibition between Member States of customs duties on imports and exports and of all charges having equivalent effect, and the adoption of a common customs tariff in their relations with third countries.

2.  Paragraph 4 and Subsection 3 shall apply to products originating in Member States and to products coming from third countries which are in free circulation in Member States.

3. Products coming from a third country shall be considered to be in free circulation in a Member State if the import formalities have been complied with and any customs duties or charges having equivalent effect which are payable have been levied in that Member State, and if they have not benefited from a total or partial drawback of such duties or charges.

4. Customs duties on imports and exports and charges having equivalent effect shall be prohibited between Member States. This prohibition shall also apply to customs duties of a fiscal nature.

5. The Council, on a proposal from the Commission, shall adopt the European regulations and decisions fixing Common Customs Tariff duties.

6. In carrying out the tasks entrusted to it under this Article the Commission shall be guided by:

(a) the need to promote trade between Member States and third countries;

(b) developments in conditions of competition within the Union insofar as they lead to an improvement in the competitive capacity of undertakings;

(c) the requirements of the Union as regards the supply of raw materials and semi­finished goods; in this connection the Commission shall take care to avoid distorting conditions of competition between Member States in respect of finished goods;

(d) the need to avoid serious disturbances in the economies of Member States and to ensure rational development of production and an expansion of consumption within the Union.