The European Union has welcomed The Appellate Body of the WTO’s decision to rule that the United States is in breach of its WTO obligations for using "zeroing" when calculating margins of dumping. "Zeroing" is a calculation methodology which consists of ignoring cases of "negative" dumping, i.e. where the export price exceeds normal value and therefore results in an artificial increase of the dumping liability of EU exporters. This decision upholds the earlier criticism of zeroing by the WTO in 2001.

EU Trade Commissioner Peter Mandelson commended the WTO decision: "Today’s ruling is a positive step in establishing a level playing field in transatlantic trade."

The Appellate Body condemnation concerns specific anti-dumping determinations in 31 cases, 15 original investigations and 16 administrative reviews, covering a wide range of products such as chemicals, steel, and ball bearings. In most cases, without "zeroing", the dumping margin may have even been negative and, therefore, no anti-dumping duty would have been imposed. Several hundred million dollars of trade volume is involved. Since its panel request in 2004, the European Commission has noted that the US has used zeroing in many other cases involving EU exporters, with the effect of inflating dumping margins.

The prohibition of zeroing thus applies to original investigations (leading to the imposition of the anti-dumping duty) as well as to investigations conducted after the imposition of the duty to revise its level, the so-called administrative reviews. According to an EU statement, if allowed to stand, a serious imbalance of rights and obligations between WTO members would have been created through opening a way out of the prohibition of zeroing for the US and other members which apply a retrospective system for the collection of anti-dumping duties.

The Appellate Body also concluded in respect of the original investigations that the United States was maintaining a methodology mandating the use of zeroing, which was then found WTO incompatible. There is no further possible appeal in this dispute and the United States will consequently have to not only revise the anti-dumping calculations in the 15 original investigations challenged by the EU, but also abandon its zeroing methodology in all of the anti-dumping original investigations.