"(c) In order to determine whether there is obvious negligence within the meaning of the second indent of Article 239(1) ... account must be taken in particular of the complexity of the provisions non-compliance with which has resulted in the customs debt being incurred and the professional experience of, and the care taken by, the trader. It is for the national court to determine, on the basis of those criteria, whether there is obvious negligence on the part of the trader."
"In determining whether this condition [reasonable detectibility] is satisfied, all the circumstances of the individual case must be assessed objectively, taking into account the nature of the error, the professional experience of the trader concerned and the degree of care which he has exercised. […] "
"… a trader whose business essentially comprises import and export transactions and who has accumulated some experience in that area must, by reading the relevant issues of the Official Journal, acquaint himself with the Community law applicable to the transactions which he undertakes."