Verizon and AT&T are also lining up in support.
Cisco and Apple have backed Microsoft’s fight against a warrant that would allow US law authorities access data stored in offshore data centres.
The companies filed a joined amicus brief supporting the software giant’s position against a warrant, issued last December, requiring Microsoft to hand over copies of emails and personal details stored on servers in Dublin as part of a criminal investigation.
Microsoft argues that search warrants for physical evidence can only be used within the United States borders, and can’t be used to "search someone’s home located in another country, just as another country’s prosecutor cannot obtain a court order in her home country to conduct a search in the United States," according to the company’s blog post.
Apple and Cisco added by ignoring that process and data protection laws in the countries where data is stored, no customer data stored by any service provider anywhere in the world would be safe from local governments.
"It also encourages foreign law enforcement to take reciprocal actions by using equivalent foreign laws to require production of data stored in the United States, despite disclosure prohibitions in U.S. law," they said.
Last week, wireless providers Verizon and AT&T, Electronic Frontier Foundation also filed petitions, saying US warrants don’t apply to emails stored on an overseas server.