The Czech Republic is not a member of the eurozone, it does not participate in the EFSF, the ESM Treaty, the Euro-Plus Pact or the Banking Union, nor is it bound by most of the provisions of the Six Pack and Two Pack legislation. It has, nonetheless, acceded to the Fiscal Stability Treaty.
The decision not to partake in the monetary integration is voluntary and relates to political dynamics that have shifted the country into the increasingly euro-sceptic direction that is coming to dominate the region. The voluntariness of this decision becomes clear when we examine the convergence criteria and the Czech legal order.
The Czech Republic has fulfilled all the convergence criteria, including the exchange rate criterion, for several years. Its constitutional order is open to further monetary and fiscal integration within or outside the EU framework.
The constitutional provisions to allow for accession to the EU are not EU-specific and as long as a new treaty transfers state competences to an international organization or institution, the internal effect of the treaty (and implementing laws) shall be governed by the same principles that have been developed by the Constitutional Court for the relationship between Czech constitutional law and EU law.