Assessing illegal trade flows based on customs and licensing scheme data

There are many possible indicators of illegal trade in environmentally-sensitive goods. In this chapter we review the evidence related to discrepancies in trade data from exporting and importing countries. Wide variations between different countries’ statistics may indicate illegal trade in some form. However, caution must be exercised. Discrepancies may indicate any one or several of a wide range of other factors such as measurement methods, data inputting or conversion errors and inconsistencies.