The term "internal market" was introduced in 1987 by the Single European Act (SEA) to indicate the removal of all obstacles to the free movement of goods, services, capital and persons. It also refers to a market with a high degree of harmonisation of laws governing trade rules, specifications of goods, etc.
Yet the treaties still refer to either the "common market", in Art. 94 TEC where laws can only be harmonisation with unanimity, or the "internal market" in Art. 95 TEC, where laws can be harmonised by qualified majority in the Council with co-decision in the EU Parliament.
The internal market can best be defined as a more uniform and thorough-going common market.
NotesSome say that the term Internal Market was only used as a pretext for introducing qualified majority voting in this area since the distinction between "internal" and "common" market is difficult.
The EU Constitution proposes the whole "internal market" to become a shared competence - EU law would therefore suppress member states' existing legislation and right to legislate in these areas .