Federal authorities in the US are using the courts to try to force American-owned technology companies to disclose emails and other data held in the Cloud - the vast network of servers where data is stored for customers.
The claim would require companies such as Microsoft, Apple and Google to open up all their electronic records to agencies, such as the CIA, the NSA and the FBI, even if it is stored in Europe rather than on US soil.
If the US government wins the case, data stored by British customers in the Cloud would be open to inspection by American investigators.
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