Spanner90, my apologies as I misread your initial post. The short answer to your first question is I am not sure, as it is not a situation I have ever come across. I imagine there would be phone calls between Duty Managers and the relevant department to ascertain the bona fides of the pax carrying the information. If it was established that the docs and the carrier were legitimate (say Defence or whatever) then I imagine they would remain sealed. This is only a guess though, and I have a hunch that material of that nature would be transferred in a Diplomatic Bag for that very reason. Any classified material of national importance would also need to be protected from the government officials of other countries.
As far as I am aware, commercial document classifications carry no weight with Customs and can be searched and read without restriction. If the info were later leaked by Customs and caused harm, I assume the company concerned would sue the Service for damages. This has been successfully done in the past (over delayed clearances of commercial goods, but I can’t remember the details) and Customs’ cargo clearance procedures were reviewed substantially. Certainly, Customs would be prosecuting and probably hanging the offending officer from the departmental flagpole as a warning to others.
As for the second, Customs have no authority to search Diplomatic Bags. Interestingly enough Quarantine do, but they have to have fairly iron clad reason. Basically unless the bag was wriggling around on the bench trying to bite people, they’d be staying well away from it, lest a diplomatic incident blow up and engulf all participants and innocent bystanders.
I think all government departments distrust all other government departments. This has also been the case in every country I have been to and read about. The yanks tried to solve it by creating another department (Dept of Homeland Security) but I think it just created another layer of distrust and angst.
This has been a good thread, it's been interesting to hear other people's opinions on a contentious subject, with a lack of media bozos and ministerial spinmeisters.