What happens if goods are shipped in packaging approved for the wrong packing group?

Shipping PG I goods in Y-marked packaging (approved for PG II and III only) or Z-marked packaging (approved for PG III only) is non-compliant under ADR Annex A, Part 4. Enforcement authorities can stop the vehicle, require the load to be removed and repacked before the journey continues, and issue penalties to both the consignor and the carrier. The consignor is responsible for selecting UN-approved packaging at the correct performance level for the packing group of their goods. The UN approval mark — X, Y, or Z — is printed on the container and must equal or exceed the packing group of every substance inside, with no exceptions regardless of transport distance or consignment size.