Tech and media companies, privacy groups and leading computer scientists all filed legal briefs on Monday backing Microsoft in a case against the US government it claims is “fundamental to the future of global technology”.

Microsoft is challenging a government order to hand over emails held on servers at its datacenter in Dublin, Ireland. The company has lost twice in court but is challenging the order in the US court of appeals for the second circuit in New York.

Technology companies including Apple, Amazon, Cisco, eBay and Verizon all filed in support of Microsoft. As have two of the US’s largest business organizations, the US Chamber of Commerce and the National Association of Manufacturers, as well as media organisations including ABC, CNN, Fox News and the Guardian.

The unusual level of cooperation among often fiercely competitive organisations comes as privacy advocates argue the US is overreaching its authority in a manner that will set a dangerous precedent for government access to online information across the world.

“We believe that when one government wants to obtain email that is stored in another country, it needs to do so in a manner that respects existing domestic and international laws. In contrast, 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,” Brad Smith, Microsoft’s general counsel, said in a blog post.

At a press conference organised by Microsoft, Victoria Espinel, president and chief executive of the software industry trade group BSA (The Software Alliance), said: “We need to think carefully about the precedent that could be set here.”

She said that allowing the US government to use the US courts to access emails stored in Ireland would allow other governments to make similar moves and demand access to information stored in the US. Such a move would damage trust in the technology sector, reduce productivity worldwide and harm privacy, she said.

News organisations, including the Guardian, have expressed concern that a victory for the US would allow Washington to go after information stored by newsrooms in the cloud. “We have stuff governments around the world want. This case may not be about digital journalism but the next case will be,” said Bruce Brown, executive director of the Reporters Committee for Freedom of the Press.

The case centres on a drug investigation currently being conducted by US authorities. Smith said the legal system already had practices in place for international crime investigations and that using the US courts to reach documents stored overseas was unnecessary and dangerous. He said in most cases Ireland already handed over documents to the US when asked through its own courts.

“The US has well-established treaties with countries around the world that allow them to seek the information they need while ensuring that citizens of other countries retain the privacy protections offered by their own laws and courts. And there’s ample opportunity for work to modernise these agreements further,” he said.