[dfawcus]

It is not just down to Commission interpretation.

It has been a while since I last looked at this, but from memory a pre-condition for Euro adoption is spending a certain amount of time within some formal "convergence mechanism", however there is no obligation to join that convergence mechanism.

This could well be ERM-II which I have in mind.

[mike_hearn]

I think you are required to join it, but proceeding to actual Euro rollout requires a currency to be within a certain range for a period of time, and that requires active intervention in currency markets. Governments can just either not do it or claim they can't intervene enough to stay on target.