Longman Dictionary of Contemporary English
Wiktionary
n. A container with letters etc from representatives of a given country to another country, which has immunity from examination by customs officials.
Wikipedia
A diplomatic bag, also known as a diplomatic pouch, is a container with certain legal protections used for carrying official correspondence or other items between a diplomatic mission and its home government or other diplomatic, consular, or otherwise official entities. The physical concept of a "diplomatic bag" is flexible and therefore can take many forms (e.g., a cardboard box, briefcase, duffel bag, large suitcase, crate or even a shipping container). Additionally, a diplomatic bag usually has some form of lock and/or tamper-evident seal attached to it in order to deter interference by unauthorized third parties. The most important point is that as long as it is externally marked to show its status, the "bag" has diplomatic immunity from search or seizure, as codified in article 27 of the 1961 Vienna Convention on Diplomatic Relations. It may only contain articles intended for official use. It is often escorted by a diplomatic courier, who is similarly immune from arrest and detention.
Usage examples of "diplomatic bag".
He'd draft it himself and send it by diplomatic bag to The Centre—.
He agreed to ring the High Commission in London and request that my passport be sent over in the next diplomatic bag.
A diplomatic bag, if possible, with full military cornucopia, just like the one we used last time.
The film and a copy of his story, he decided, would find their way into the diplomatic bag.
The letter and the report went into the diplomatic bag and caught the evening flight by El Al from Heathrow to Ben-Gurion.
The diplomatic bag, which actually is a bag, or at least a series of canvas sacks, goes from Moscow to London every Wednesday and always on the British Air-ways flight, never Aeroflot.
He never bothered himself wondering what he carried in the diplomatic bag, or in this metal case in his coat.
So he piggybacked the information through the diplomatic bag several days before the balloon went up and had it remailed to a private account in Nouveau Paris after the bag got here.
Now, it seems that whoever mount-ed the Semyonov incursion has taken a policy decision not to use the Soviet Embassy's diplomatic bag.
From the locker the Russian withdrew a package, sealed exactly as when it had arrived in the diplomatic bag at the embassy two days earlier.
The weapons had come in the diplomatic bag to Madrid, along with the two-way radios and the drugs that might be needed if Red Rose became dangerously hysterical on seeing her son.
The courier was flying Aeroflot to Heathrow with a diplomatic bag, which was inviolable so long as the courier kept it in his possession countries had been known to steal them for their contents, which were often uncoded, but couriers knew about that, and played by a strict set of rules-if they had to visit the can, so did the bag.