Microsoft said Monday it had secured broad support from a coalition of influential technology and media firms as it seeks to challenge a US ruling ordering it to hand over emails stored on a server in Ireland.
The US technology giant, which says it has the backing of global heavyweights including Apple and Amazon, has for several months defied a court-ordered search warrant aimed at giving US agents investigating drug-trafficking access to a customer's emails.
As part of an appeal against the ruling, which tests the limits of US authorities' right to access data stored outside the United States, Microsoft has been building support from other companies who have backed its case.
The company released 10 letters submitted to the court signed by 28 leading technology and media companies, as well as 35 prominent computer scientists and nearly two dozen trade associations and advocacy groups.
Among those voicing support were computer titans such as Apple, HP and CISCO, as well as online giants including Amazon and eBay, along with telecom companies such as AT&T and Verizon. Media companies included The Washington Post, Forbes, The Guardian, CNN and Fox News.
"Seldom has a case below the Supreme Court attracted the breadth and depth of legal involvement we're seeing today," Brad Smith, Microsoft's general counsel, wrote in a blog post.
"This case involves not a narrow legal question, but a broad policy issue that is fundamental to the future of global technology," he added.
"The US government's unilateral use of a search warrant to reach email in another country puts both fundamental privacy rights and cordial international relations at risk."
The case comes amid rising concern about US surveillance following revelations of snooping disclosed by former National Security Agency contractor Edward Snowden.
Nuala O'Connor, president of the Center for Democracy and Technology, said that "if the US government wins this case, it would severely undermine trust in the global cloud.
"It would certainly lead to other countries demanding, through their own domestic legal regimes, access to communications content stored in the US on behalf of Americans and others."
BSA president Victoria Espinel added that "the government's position would have a chilling effect on the international market for cloud-based services."