Export controls

Trade barriers are government-induced restrictions on international trade. The barriers can take many forms, including the following:

Most trade barriers work on the same principle: the imposition of some sort of cost on trade that raises the price of the traded products. If two or more nations repeatedly use trade barriers against each other, then a trade war results.

Economists generally agree that trade barriers are detrimental and decrease overall economic efficiency; this can be explained by the theory of comparative advantage. In theory, free trade involves the removal of all such barriers, except perhaps those considered necessary for health or national security. In practice, however, even those countries promoting free trade heavily subsidize certain industries, such as agriculture and steel.

High income countries tend to have less trade barriers than middle income countries which, in turn, tend to have less trade barriers than low income countries. Small states tend to have lower trade barriers than large states. The most common trade barriers are on agricultural goods. Textiles, apparel and footwear are the manufactured goods which are most commonly protected by trade barriers. Tariffs have been declining in the last twenty years but states have increased their non-tariff barriers.

According to Chad Bown and Meredith Crowley, world trade is "probably" vastly more liberal in current times than was the case historically. According to Ronald Findlay and Kevin H. O’Rourke, "for the nineteenth and twentieth centuries trade barriers and transport costs were the most important barriers to trade". They also write, "during the mercantilist era price gaps were as likely to be due to trade monopolies, pirates, and wars as to transport costs and tariffs, which are more easily quantifiable."

Georgetown University Professor Marc L. Busch and McGill University Professor Krzysztof J. Pelc note that modern trade deals are long and complex because they often tackle non-tariff barriers to trade, such as different standards and regulations, in addition to tariffs. Due to steadily decreasing tariff barriers since WWII, countries have become increasingly likely to enact trade barriers in the form of non-tariff barriers. National firms often lobby their own governments to enact regulations that are designed to keep out foreign firms, and modern trade deals are one way to do away with such regulations.

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Wikipedia