Competence is an interesting word. In everyday English, it means capability, the capacity to deal adequately with a subject (cf OED). In EU-speak, however, it means something rather different: the sole right and power to legislate in a particular area.
When we hear that trade is a sole competence of the European Union, or that a binding interpretation of EU law is the sole competence of the Court of Justice of the European Union, we need to understand its significance: in these areas of national and international policy, Britain (along with other ‘member states’) has ceded to the European Union sole power to pass laws which bind the actions of British citizens.
And since the sole power to initiate EU legislation rests with the European Commission — unelected, undemocratic and unaccountable — we have no right, power or opportunity to oppose it. This is insupportable.