Microsoft does not have to comply with a US search warrant for an email stored in its Irish data center, according to a federal appellate court decision handed down today.

In her decision, Judge Susan Carney of the US Court of Appeals for the Second Circuit explained that the warrant, which directed Microsoft to produce the contents of an email account and associated customer data stored in Ireland, is invalid.

"Interpreting 'warrant' to require a service provider to retrieve material from beyond the borders of the United States," Carney wrote, would violate the "presumption against extraterritoriality" established by the Supreme Court.

The case began in late 2013, when a US district court ordered Microsoft to turn over customer email data stored in a Dublin data center. The company refused and appealed the decision, sparking a court battle that was backed by several other tech companies, including Verizon, Apple, Amazon, HP, eBay, and AT&T.

"We obviously welcome today's decision by the Second Circuit Court of Appeals," Microsoft's Chief Legal Officer Brad Smith said in a statement. "The decision is important for three reasons: it ensures that people's privacy rights are protected by the laws of their own countries; it helps ensure that the legal protections of the physical world apply in the digital domain; and it paves the way for better solutions to address both privacy and law enforcement needs."

Industry representatives also celebrated Microsoft's victory, including the Computer & Communications Industry Association, which called it an important decision for privacy protections and the rule of law.

"As Congress considers reforming the Electronic Communications Privacy Act and Stored Communications Act, this ruling demonstrates the importance of clear statutory language that anticipates and facilitates cloud privacy and security," CCIA director of external affairs Maggie Brenan said in a statement.