But there are limits to the effectiveness of national action. Gaps are left wh
ich only the EU can fill. In order to reach its objectives, from the very outset the Treaty assigned a central role to fully-fledged common policies such as competition, trade, transport, agriculture and fisheries, and more recently EMU. There cannot be a true internal market and a customs union without precise rules to establish a level pla
ying field. Without harmonising the great diversity of Member State policies, internal border controls would have had to be
maintaine ...[+++]d, the EU could not have spoken with one voice in international trade and sustainability would have suffered in a downward spiral of negative competition.