Antidumping duties are usually not retroactive. But a definitive antidumping duty may be levied retroactively on products imported not more than 90 days prior to the date of publication and application of provisional remedies, if 1) there is a history of dumping of the product which causes injury or the importer was, or should have known the practice of dumping by the exporter and such practice would cause injury; and 2) the volume of dumped products sharply increased in relatively short period of time and has already caused injury to domestic industry.
