How bad is opening an embassy's diplomatic pouch?

Assume it’s an honest mistake by a customs inspector. If it will somehow affect things, the country with an embassy is Japan, and the pouch contains personal items for use by their emperor during an ongoing state visit.

It would probably fall into the same category as viewing classified government documents. If you inadvertently happen to see the contents, all you need to do is to refrain from revealing what you have seen, publicly or privately, and not tamper with the contents in any way. (I learned that on X-Files tonight.)

It’s definitely a candidate for someone’s worst faux pas.

That’s what people here in the Philippines are saying. A customs agent opened a pouch meant for Emperor Akihito, who’s currently here on a state visit.

A pouch can contain anything from a top secret document to your personal vehicle and the entire contents of your home. It’s not what’s in there that’s necessarily important, it’s the agreement between nations that the pouches are inviolate that matters. They have certainly been abused in the past by people shipping contraband (such as elephant ivory or antiques) out of a country.