A trade restriction is an artificial restriction on the trade of goods between two countries. It is the result of protectionism. However, the term is controversial because what one part may see as a trade restriction another may see as a way to protect consumers from inferior, harmful or dangerous products. For instance Germany required the production of beer to adhere to its purity law. The law, originally implemented in Bavaria in 1516 and eventually becoming law for newly unified Germany in 1871, made many foreign beers unable to be sold in Germany as "beer". This law was struck down in 1987 by the European Court of Justice, but is still voluntarily followed by many German breweries.

Rectangular headlamps were promoted in the United States where round lamps were required until 1975. By 1979, the majority of new cars now had the rectangular headlamps. Again, the U.S. permitted only two standardized sizes of rectangular sealed-beam lamp: A system of two 200 mm x 142 mm high/low beam units corresponding to the existing 7" round format, or a system of four 165 mm x 100 mm units (two high/low and two high-beam) corresponding to the existing 5¾ inch (146 mm) round format.