To follow-up on our earlier posting, we wanted to make some additional points. First, it is important to emphasize that any question of rebutting a presumption of nullification or impairment is closely tied to the facts of the particular case. It's a difficult question to answer in the abstract. Therefore, the easiest way to think through the issue may be to give some examples. In the earlier posting, we gave the example of a failure to notify in a situation where the information was available publicly and was actually known by the complaining government. The only other example we've been able to think of is a slight variation on the situation in Bananas. Imagine that Country A adopts a measure which explicitly discriminates against a foreign product (say, coal) from Country B, and a violation is found. If it could be demonstrated that Country B has no coal reserves and therefore no possible involvement with coal production, perhaps a case could be made that no nullification or impairment exists.These two examples are illustrations of situations in which an argument could be made that the presumption of nullification or impairment has been rebutted. However, for all practical purposes, it seems very unlikely that a presumption of nullification or impairment will be rebutted. The examples we gave will rarely occur in the real world. With regard to the coal example, it is important to keep in mind that even a potential export interest or an effect on the internal market can lead to a finding of nullification or impairment (see Bananas). It would take an extreme situation in order for a country not to face such effects. As for the notification example, it would be hard to prove that government officials had actual knowledge of the relevant information, as they are unlikely to make definitive public statements on such a matter.
As to the relationship of rebutting the presumption of nullification or impairment with the concept of "harmless error," we confess at the outset that we do not know a great deal about the application of this principle in the public international law arena. However, there appears to be some overlap between the two concepts. In a sense, a demonstration that a violation of WTO rules has not caused nullification or impairment is similar to a showing that it was a harmless error. It's a finding that the harm caused by the violation was de minimis, and therefore can be ignored. Given the AB's recent citation to international law principals (both good faith and proportionality), it seems like it might be worthwhile to make the argument. Of course, it would first have to be proved that harmless error has risen to the level of a principle of international law, something the Guatemala - Cement II panel rejected.