There are some economically valid arguments in favor of trade restrictions. The major ones are:
-
Dumping:
Dumping is the practice of selling goods in a foreign market at a price lower
than that which prevails in the domestic market. The intent is (presumed to be)
to drive domestic producers out of business, after which a price hike can be
expected.
-
Countervailing
Duties: If goods are produced in a nation where the industry is subsidized, and
then sold in a nation where no such subsidy exists, then domestic producers
will be at a competitive disadvantage to imports from the subsidizing nation.
Where such an imbalance exists, it is acceptable to impose a tariff intended to
just equal the advantage provided by the subsidization.
-
Squeaky
Wheels: While on average everyone benefits from free trade, individually some
people lose badly—because they are laid off, or their business cannot compete,
or what have you. It is difficult to build a political organization a large
number of small gainers, but it is relatively easy to build a political
organization around a small number of big losers; say, unemployed steel workers
in Pennsylvania. While theoretically it is possible for the losers to be
compensated from the benefits of the gainers, in practice this rarely (if ever)
happens.