It is important to remember from a control perspective that goods exported from one particular country do not necessarily originate in that country.
For example, ADD may apply to bicycles from China. In order to avoid this, traders may send the parts to Vietnam for simple processing and then claim Vietnamese origin.
Circumvention takes place when the normal pattern of trade between an exporting country and the EU is altered specifically to avoid paying ADD/CD. If there is any doubt as to the correct origin of a given product, then a Certificate of Origin showing the name of the manufacturer and/or the exporter should be requested.