Microsoft has defied a court order to release a customer's emails stored overseas to US prosecutors while it appeals the lifting of a suspension on the order.
Microsoft had been ordered to hand over the emails to US prosecutors as part of a search warrant for the information, which is stored inside a Microsoft data centre in Ireland.
But a US district judge delayed enforcement of the US Government's search warrant to allow Microsoft to appeal, and issued a stay in July.
Following arguments from prosecutors who said there was legal reason to enforce the stay, the district judge this weekend agreed and lifted her suspension of the order.
Microsoft continues to refuse to comply with the judge's order and promised to appeal the decision.
It has committed to fighting the warrant to protect the privacy of its customers.
"Microsoft will not be turning over the email and plans to appeal,” a spokesperson said.
"Everyone agrees this case can and will proceed to the appeals court. This is simply about finding the appropriate procedure for that to happen."
The judge ordered both sides to advise by September 5 how to proceed.
The case appeared to be the first in which a corporation has challenged a US search warrant seeking data held abroad.
AT&T, Apple, Cisco, and Verizon Communications have submitted briefs supporting Microsoft's opposition to the warrant.
The companies are fearful of losing revenue from foreign customers worried that US law enforcement might win broad power to seize their data.