Un complément d’info :

Parliamentary questions 12 January 2012 E-010760/2011 Answer given by Mr Rehn on behalf of the Commission

In 2002, a G-10 working group issued a report on collective action clauses (CAC) recommending the creation of a structure building on existing practices to promote a consistent framework across jurisdictions for eventual sovereign debt crises. In 2003, the European Union Member States agreed to lead by example in including such clauses in their international bond issuance. The implementation, however, is not uniform. The contents of the CAC may vary according to under which law (e.g. English, New York, Japan etc.) the bonds are issued.

As regards sovereign issuance under domestic law many Member States do not apply such clauses.

http://www.europarl.europa.eu/sides/getAllAnswers.do?reference=E-2011-010760&language=FR