As for the unanimity rule on general foreign policy, the Council can agree to adopt different procedures, including qualified majority voting, albeit triggered unanimously (Art 31 CTEU). Irish governments may feel obligated …. that word again … so a form of moral and political pressure will compel them to avoid being in a minority of one scenario. Moreover, even when abstaining, there is wording in the Treaty that encourages (not compels, but encourages) them to agree to act in a manner not incompatible with the measures they refused to support in the open. There is a lot about “solidarity” – again, a coercive normative framework for putting pressure on dissenters. This framework is as much about political coercion as about legalities.
There is continuing discussion of Article 48. The article requires national constitutional procedures (referenda in Ireland) for instances of both kinds of Treaty amendment. Yet, there is still an option for a Council decision to apply QMV to new areas within the general competences already granted to the Union. That formulation remains extremely slippery and open to abuse by politicians and politically-biased judges. Yes campaigners (as here – Michael McLoughlin’s well-constructed – even if misguided YES site), have generally glossed over the potential for mischief arising from the ambiguities in articles 31 and 48. Measuring the weight and significance of foreign policy issues that should require QMV and those that should not is a very complex matter. Similarly, the boundaries between policy and implementation measures are easily fudged.
States are allowed to cite national interest as a reason for rejecting QMV decision-making. But, in this case, there is an effort on the part of the Council and the head of CFSP to “resolve” the difference, another opportunity for moral and political coercion.