Most of the sections in IMDG Code prescribes the action but does not specifically point out the party or person who is responsible for that action. The shoulder(s) which need to bear the responsibilities of actions set out in IMDG Code may vary according to the individual countries laws. It remains the prerogative of each government to assign the respective responsibilities.
However regarding Classification of dangerous goods IMDG Code specifically states it is the responsibility of shipper or the competent authority where specified in the Code.
Responsibility of classification of most of the classes remains with shipper but IMDG Code delegates the responsibility to competent authority in below cases
Class 1 ( Explosives ) : Classification shall be approved by the competent authority of the country of manufacture.
Class 4.1 Self-reactive substances: Which are not listed in section 2.4.2.3.2.3, IBC520 or T23
Class 5.2 Organic Peroxides: Which are not listed in section 2.5.3.2.4, IBC520 or T23