A diverse group, ranging from Apple to CNN, is backing Microsoft in its legal clash with the U.S. government over access to emails stored overseas. (Reuters)

Ten groups of top technology, media and business organizations on Monday filed legal briefs in support of Microsoft’s argument to a federal appeals court that the U.S. government cannot issue a search warrant to obtain customers’ e-mails held in another country.

The unusually high number of friend-of-the-court briefs and the breadth of groups that signed on reflect how significant the issue of privacy in the digital age is to U.S. industry.

“This is not a case about a narrow legal issue but rather a broad policy issue that is of profound importance to the future of the Internet,” Brad Smith, Microsoft general counsel, said in an interview Monday.

Many of the tech companies, including cloud-computing firms that have tens of billions of dollars in overseas sales, have joined with Microsoft on the legal principle as well as out of fear that they will lose the trust of foreign customers, sending them fleeing to non-U.S. firms.

“Allowing the government to use such a warrant would expose U.S. companies to legal jeopardy in other countries which prohibit the disclosure of such data and spur retaliation by foreign governments, which would threaten the privacy of Americans,” said Randal S. Milch, general counsel of Verizon Communications, which filed an amicus brief with other technology companies.

Microsoft Corp. CEO Satya Nadella, left, and CFO Amy Hood take questions Dec. 3 at Microsoft’s annual shareholder meeting in Bellevue, Wash. An unusual number of briefs was filed in support of the company’s case over searches of customer e-mails. (Ted S. Warren/AP)

Microsoft’s battle with the U.S. government began a year ago, when a magistrate judge in New York issued a search warrant for a customer’s e-mails held in a Microsoft data center in Ireland and connected to a drug-trafficking investigation.

Microsoft resisted the warrant, arguing that it was grounded neither in U.S. law nor the Constitution. A U.S. District Court judge in July upheld the December 2013 warrant, and Microsoft appealed last week.

Speaking on a Microsoft-
sponsored panel Monday
, Smith said that if the Redmond, Wash., company loses, “we expect foreign governments are going to lay down more rules that will make it more difficult for us to serve our customers.”

Two of the largest business organizations, the U.S. Chamber of Commerce and the National Association of Manufacturers, filed briefs discussing the case’s implications for the U.S. economy. Five leading civil liberties groups filed briefs arguing that privacy rights are at stake. And 17 major media companies, including The Washington Post, submitted briefs expressing concerns that the decision, if upheld, would erode legal protections that have restricted the government’s ability to search reporters’ e-mails.

Microsoft has argued that the United States has well-
established treaties with other governments that allows it to seek information without resorting to extra-territorial claims.

Smith said in the interview Monday that Microsoft supports legislation that would enable U.S. law enforcement authorities to extend their reach overseas — to serve a search warrant for data held in a server in Europe, for instance — if it were confined to data of U.S. citizens or residents.

“The German government, for example, would know that this is not something that is going to put at risk the privacy rights of German citizens who were living in Germany,” he said. “So, I do think it’s the kind of path that would strike an appropriate balance.”