Replying to [kai1]:
Normally, when an exporter books a container, he tells the shipping agnet what he wants to ship. The empty container is then delivered to the exporter's address, where it is loaded, doors closed, and sealed.
This is why you will see on all BLs the words "shippers load, count and seal" which means the shipper loaded the container, counted the goods, sealed the container, and is therefore responsible as to what and how many are shipped.
If he declares new computers and ships rubbish instead, he can do so, and the shipping company is not responsible. After all, they are contracted to just transport the Container, NOT what's in it.