[SAJ]

NSA and CIA are indeed so prohibited. However, there is no prohibition at law against NSA/CIA/USwhomever listening in/monitoring citizens of the UK ... and similarly there is no prohibition at law against MI6 listening in/monitoring citizens of the US.

This curious little legal quirk has matured over the years into Echelon and related systems.

[NotJustAnotherPrettyFace]

Right.... and the free-sharing of information. However, this IS one of the things that drives the rest of the Euros crazy ;-).

[Grampa Dave]

Bingo:

"NSA and CIA are indeed so prohibited. However, there is no prohibition at law against NSA/CIA/USwhomever listening in/monitoring citizens of the UK ... and similarly there is no prohibition at law against MI6 listening in/monitoring citizens of the US."

"This curious little legal quirk has matured over the years into Echelon and related systems."

Then, throw the Mossad and KGB into this mix, and the Islamofascist trolls who use the internet as a communication or PR tool, could be in for a knock, knock game.