What swung it for me was the actual constitutional ammendment;

“No provision of this Constitution invalidates laws enacted, acts done or measures adopted by the State that are necessitated by the obligations of membership of the European Union referred to in subsection 10° of this section, or prevents laws enacted, acts done or measures adopted by the said European Union or by institutions thereof, or by bodies competent under the treaties referred to in this section, from having the force of law in the State.”

which to me is totally unacceptable.