A lawsuit filed by Microsoft against the U.S. Justice Department Thursday could determine the future of privacy in the cloud, Microsoft’s chief legal officer told Geekwire.

The suit challenges the federal government’s use of secrecy orders to compel Microsoft and other technology companies to turn over customers’ information—without informing customers that they are targets in an investigation.

Such orders have become more common in recent years, with Microsoft fielding about 5,600 requests from government investigators for customer data in the last 18 months, according to The New York Times. Almost half of those were accompanied by gag orders barring the company from discussing them with customers.

“We’re raising this because of the implications for where technology is going,” Microsoft chief legal officer Brad Smith told Geekwire. Customers who store their data, including email, in cloud servers have the expectation of privacy. But unlike when the government searches physical files—seizing hard drives and documents—targets of an investigation aren’t likely to know that their electronic files are being searched unless the service provider tells them.

“It is very important to businesses to defend themselves when the government is investigating them…but none of that is possible if the business doesn’t even know that the government is obtaining their emails and I think for most people in business, that is both disconcerting and sometimes even shocking,” said Smith.

Especially troubling, said Smith, is the fact that so many secrecy orders are open-ended, meaning Microsoft can basically never tell the customer that their files have been searched.

The suit contends that the portion of Electronic Communications Privacy Act of 1986 which authorizes the secrecy orders is unconstitutional. It violates both the Fourth Amendment rights of customers to know when their property is being searched or seized and the First Amendment right of Microsoft to communicate freely with its customers, the company argues.

The Justice Department hasn’t made a public statement about the suit, but has argued in the past that secrecy orders prevent subjects from tampering with or destroying evidence after they learn about an investigation.

While Apple’s recent clash with the FBI over unlocking an iPhone belonging to one of the San Bernardino attackers has drawn quite a bit of attention, the implications of Microsoft’s lawsuit may be more far-reaching. Rather than defensively responding to a particular demand from the government, Microsoft is going on the offensive, challenging the Feds’ entire rationale for secretly seizing customer information.

Smith told the Times he expects other tech companies to join the suit. Some, like Yahoo, have already publicly expressed their support. You can view a copy of the official complaint, filed in Federal District Court in Seattle, here.