The European Coal and Steel Community (ECSC) was administered by a High Authority with legislative, executive and judicial competence – in a very limited area of coal and steel. The aim was to have common control over the resources used for war.
That is the historical background and predecessor to the even more powerful EU Commission, which has the monopoly on initiating laws in the EU.
The EU Commission makes laws for a very broad range of areas, traditionally belonging to parliamentary democracies. This development has contributed to the discussions on democratic deficit and democratic legitimacy.