Microsoft has aligned itself with Google to push the US government towards greater transparency on access to customer information in the wake of the PRISM surveillance scandal.
Microsoft's general counsel Brad Smith posted on the firm's TechNet blog, painting the picture of a united front as the two rival companies both press on with lawsuits filed in June to persuade the government to publish details of its user data requests.
"To followers of technology issues, there are many days when Microsoft and Google stand apart," he said. "But today our two companies stand together. We both remain concerned with the government's continued unwillingness to permit us to publish sufficient data relating to Foreign Intelligence Surveillance Act (FISA) orders."
He acknowledged the US government's recent move to annually publish the total number of customer data requests relating to national security, but said that it did not go far enough. "The public deserves and the Constitution guarantees more than this first step," he insisted.
Smith argued that the plans should go further, demanding the inclusion of more information about each request, including whether it is a request for content such as that of an email.
"We believe it's possible to publish these figures in a manner that avoids putting security at risk. And unless this type of information is made public, any discussion of government practices and service provider obligations will remain incomplete," he said.
So far, the US government is yet to respond to the firms' requests, with Microsoft agreeing to extend the deadline of its lawsuits. Smith said he was "disappointed" that negotiations had so far failed and so the firms would continue with their legal efforts.
"With the failure of our recent negotiations, we will move forward with litigation in the hope that the courts will uphold our right to speak more freely," he said.
Smith previously took to the TechNet blog in July in response to issues highlighted by NSA whistleblower Edward Snowden, posting a detailed summary of how Microsoft responds to data requests made to each of its online services including Outlook, Skype and enterprise email.
Two days later, the firm joined Apple, Facebook and Yahoo, plus another 18 technology companies in writing an open letter to US president Obama on the subject of transparency.
The US government insists its practices are within the law, but this has not stopped widespread public and industry condemnation of its actions.