Since December 2013 Microsoft have been fighting US efforts to make them export data, arguing that a U.S. judge has no authority to issue a warrant for information stored abroad.
What does this mean for European business? Even if you use a US firm that hosts in Europe, they are still likely to export that data to the US government on request* (not everyone is going to go to court on this, it’s easier to just comply with a court order – and hey it’s secret, so nobody will know!)
It is possible that the EU will introduce a new safe harbor style agreement, but it’s unclear how any agreement can stop the US Government asking US business to share data.
Full story – https://en.wikipedia.org/wiki/Microsoft_Corporation_v._United_States_of_America
*European firms can of course also be forced to disclosed information under Mutual Legal Assistance Treaties, but an MLAT request would require international co-operation, and could not be done secretly.