A Free Trade Area is a region in which obstacles to unrestricted trade have been reduced to a minimum.
Within an industrialized country there are usually few if any significant barriers to the easy exchange of goods and services between parts of that country. For example, there are usually no trade tariffs or import quotas; there are usually no delays as goods pass from one part of the country to another (other than those that distance imposes); there are usually no differences of taxation and regulation.
Between countries on the other hand many of these barriers to the easy exchange of goods often can and do occur. It is commonplace for there to be import duties of one kind or another (as goods enter a country) and the levels of sales tax and regulation often vary by country.
The aim of a free trade area is to so reduce barriers to easy exchange that trade can grow as a result of specialisation, division of labour, and most importantly via (the theory and practice of) comparative advantage. The theory of comparative advantage argues that in an unrestricted marketplace (in equilibrium) each source of production will tend to specialize in that activity where it has comparative (rather than absolute) advantage. The theory argues that the net result will be an increase of income and ultimately wealth and well-being for everyone in the free trade area.
The theory of comparative advantage rests on the necessary condition of "capital immobility." If financial (or labor) resources can move between countries, then the comparative advantage theory erodes, and absolute advantage dominates. Given the liberalization of capital flows under free trade agreements of the 1990s, the necessary condition of capital immobility no longer holds. As a consequence, the economic theory of comparative advantage no longer supports free trade theory.
