For most Americans, Japan is seen as being at the heart of the unfair trade problem. There is strong evidence that the Japanese government and Japanese companies in the auto and steel industries -- to name but a few - have not always traded fairly.

But most Americans are probably not aware that the United States has experienced a virtually identical problem with Mexico, its neighbor to the south and partner in the North American Free Trade Agreement. Surprisingly, the Mexican cement industry employs unfair tactics virtually identical to those used by mercantilists from Japan.

This issue is topical because the U.S. government is considering lifting a duty on Mexican cement that was imposed to counter dumping -- sales of goods at less than their price in the home market or less than their cost of production.

At first blush, the position that the government should eliminate duties on cement and allow consumers to pay a lower price seems reasonable. Anti- dumping duties, however, serve a vital public purpose.

Dumping is not simply the result of a temporary overstock situation, a seasonal sale, or an exchange rate miscalculation. Such innocent mistakes are effectively exempt under international law.

Dumping is the result of a systematic, mercantilistic trade strategy. Usually, it involves a foreign company that enjoys a closed home market, which allows it to raise prices and generate high profit at home.

These foreign companies then sell at much lower prices in foreign markets (often the United States) in order to keep production levels high, maximize market share, and put pressure on competitors that do not enjoy closed home markets.

This has been a pattern repeated time and time again by Japanese steel producers, Korean semiconductor companies and a number of Chinese companies, among others.

Mexico is certainly quite different from Japan and Korea, but the behavior of the Mexican cement industry is functionally identical to that of Japanese and Korean dumpers.

The Mexican cement market is simply not competitive; it is controlled by a trust led by one dominant company: Cemex, which controls almost two-thirds of the Mexican market.

Because of collusion between Cemex and other producers, Mexican consumers pay cement prices far above the competitive market price. According to recent information, Mexican consumers pay as much as $69 more than U.S. importers for a ton of cement; the price to U.S. importers is $31 a ton, far below the home-market price.

To ensure that they can continue to charge these high prices, Mexican cement companies work with the supply chain to limit imports to less than 1 percent of the Mexican market.

The Mexican cement industry exports a substantial amount of cement at cut- rate prices to keep capacity utilization and employment high. The high profit at home makes these sharp price cuts on exports possible. Effectively, Mexican consumers are paying an export subsidy on each and every ton of cement exported from Mexico.

But Mexican consumers are not the only victims of this strategy. U.S. cement producers, who must sell their cement production into a competitive market, are also hurt.

Mexican cement producers have for years sold their cement into the U.S. market at a dumped price in order to make sales. In every annual review of the pricing practices of Mexican companies, the U.S. Commerce Department has found Mexican cement companies to be dumping cement in the U.S market, sometimes at less than half the price of cement in Mexico.

Before anti-dumping duties were placed on Mexican cement in 1990, U.S. producers were losing sales to dumped Mexican production, which forced layoffs of U.S. workers and even shutdowns. Since the order, U.S. producers have steadily expanded capacity to meet U.S. demand.

Of course, the ideal solution to this problem is for the Mexican government to enforce competition in the Mexican cement market, break Cemex's hold, and allow imports from the United States and elsewhere. Unfortunately, this preferred solution is not very realistic given the political influence of Cemex and the apparent unwillingness of the Mexican government to insist on open competition.

Hopefully, conditions will change in Mexico at some point, and the market will become truly competitive and open to imports. When that happens, dumping will naturally cease and anti-dumping duties will not be needed.

But until that happens, it is unwise to force U.S. cement producers to compete on an unlevel playing field. The anti-dumping duties should remain in place.