3.) The right of each nation to determine which items may or may not be transmitted through that nation's postal system; including but not limited to hazardous or illegal materials.
I agree with the Gobbannean Ambassador, this clause is quite toothless, other than that, the revised version which Lord Tyvok offered is quite an admirable piece of legislation.
To amend this clause, I would suggest allowing nations to limit the mailing of physically hazardous material (more severely hazardous than a paper cut, hopefully), and not to worry about illegal materials, which can be recovered by force once they are recieved.