Though prospects for broad reform of the U.S. antidumping law are tied to the now-moribund Doha Round of trade negotiations, curtailing antidumping abuse is still viable through other channels. Yesterday, the Appellate Body of the World Trade Organization ruled that the U.S. dumping calculation technique known as “zeroing” violates the WTO’s Antidumping Agreement.

In determining margins of dumping (which dictate the prospective antidumping duties applied to affected imports), the Department of Commerce typically compares a foreign exporter’s U.S. and home market prices. There are usually dozens or hundreds (sometimes thousands) of comparisons made, each generating a margin of dumping, which can be positive, negative or zero.

Before averaging the individual dumping margins to produce an overall antidumping duty rate, the DOC perpetrates some sleight of hand by setting all of the negative dumping margins to zero. This, of course, has the effect of seriously inflating the overall rate and dissuading subsequent importation.

Zeroing is probably the most distortive of a multitude of methodological tricks the DOC undertakes in the name of fighting unfair trade. In previous research, Brink Lindsey and I looked at 18 actual dumping cases and found that had the DOC not engaged in zeroing, the antidumping duty rates would have been, on average, 89 percent lower.

If the United States complies with yesterday’s ruling and ceases the practice in all cases prospectively, the antidumping law will remain a nuisance, but its capacity to seriously obstruct trade will be weakened considerably.