The tasks of the European System of Central Banks (ESCB) and the Eurosystem are laid down in the Treaty on the Functioning of the European Union. They are specified in the Statute of the European System of Central Banks and of the European Central Bank. The Statute is a protocol attached to the Treaty.
The Treaty on the Functioning of the European Union generally refers to the ESCB rather than to the Eurosystem, since it was drawn up on the premise that all EU Member States would eventually adopt the euro. The Eurosystem is made up of the ECB and the national central banks (NCBs) of the EU Member States whose currency is the euro, whereas the ESCB comprises the ECB and the NCBs of all EU Member States (Article 282(1) of the Treaty). As long as there are EU Member States whose currency is not the euro, it will be necessary to make a distinction between the Eurosystem and the ESCB.
Article 127(1) of the Treaty defines the primary objective of the Eurosystem:
"The primary objective of the European System of Central Banks […] shall be to maintain price stability".
It continues as follows: "Without prejudice to the objective of price stability, the ESCB shall support the general economic policies in the Union with a view to contributing to the achievement of the objectives of the Union as laid down in Article 3 of the Treaty on European Union."
The European Union has multiple objectives (Article 3 of the Treaty on European Union), which include the sustainable development of Europe based on balanced economic growth and price stability, and a highly competitive social market economy, aiming at full employment and social progress. Consequently, price stability is not only the primary objective of the ECB’s monetary policy, but also an objective of the European Union as a whole. Thus, the Treaty on the Functioning of the European Union and the Treaty on European Union establish a clear hierarchy of objectives for the Eurosystem, making it clear that price stability is the most important contribution that monetary policy can make to achieving a favourable economic environment and a high level of employment.