While the concept of a "social market economy" was only introduced into EU law in 2007, free movement and trade were central to European development since the Treaty of Rome 1957. According to the standard theory of comparative advantage, two countries can both benefit from trade even if one of them has a less productive economy in all respects. Like in other regional organisations such as the North American Free Trade Association, or the World Trade Organisation, breaking down barriers to trade, and enhancing free movement of goods, services, labour and capital, is meant to reduce consumer prices. It was originally theorised that a free trade area had a tendency to give way to a customs union, which led to a common market, then monetary union, then union of monetary and fiscal policy, political and eventually a full union characteristic of a federal state. In Europe, however, those stages were considerably mixed, and it remains unclear whether the "endgame" should be the same as a state, traditionally understood. In practice free trade, without standards to ensure fair trade, can benefit some people and groups within countries (particularly big business) much more than others, but will burden people who lack bargaining power in an expanding market, particularly workers, consumers, small business, developing industries, and communities. The Treaty on the Functioning of the European Union articles 28 to 37 establish the principle of free movement of goods in the EU, while articles 45 to 66 require free movement of persons, services and capital. These so-called "four freedoms" were thought to be inhibited by physical barriers (e.g. customs), technical barriers (e.g. differing laws on safety, consumer or environmental standards) and fiscal barriers (e.g. different Value Added Tax rates). The tension in the law is that the free movement and trade is not supposed to spill over into a licence for unrestricted commercial profit. The Treaties limit free trade, to prioritise other values such as public health, consumer protection, labour rights, fair competition, and environmental improvement. Increasingly the Court of Justice has taken the view that the specific goals of free trade are underpinned by the general aims of the treaty for improvement of people's well being.