The derogation from adopting the euro
The provisions relating to the derogation (temporary exemption) laid down in Articles 139–140 of the Treaty and problems complying with the convergence criteria gave rise to the possibility of a “multi-speed” Europe being created. This would ultimately have meant the formation of zones with higher and lower levels of integration.
This possibility, which up to then had been more of a theoretical one, was strengthened during the creation and approval of the Maastricht Treaty, when the United Kingdom and subsequently Denmark secured permanent opt-outs from having to introduce the single currency. This means they will adopt the single currency not automatically after having satisfied the convergence criteria, but rather on their request. The multi-speed issue was intensified by the enlargement of the EU at the start of the new millennium and by different views regarding the need for fiscal responsibility in the northern and southern EU Member States.