Microsoft is headed back to court this week in its long-standing effort to fight a U.S. Department of Justice search warrant seeking access to a crime suspect’s digital documents stored on a server in Ireland.

The company, on the losing side of two lower court decisions, including one from mid-2014, will argue its case before the U.S. Court of Appeals for the Second Circuit on Wednesday.

Microsoft and its allies have argued that the DOJ didn't have the authority to seek the December 2013 search warrant, related to a New York criminal case, because the suspect's data resides in Dublin data center. If the DOJ insists its search warrants extend to overseas data, the agency will expose U.S. citizens' data to searches by other governments, Microsoft has argued.

The case raises questions about law enforcement reach and data privacy, said Craig Newman, a cybersecurity lawyer at the Patterson Belknap Webb & Tyler law firm in New York City.

"If the U.S. government is permitted to serve warrants on U.S. technology companies and obtain email that is stored in other countries, will it cause other countries to serve warrants on tech companies for the private communications of American citizens stored in U.S. data centers owned by foreign companies?" Newman and colleague George LoBiondo wrote in a recent blog post.

Will U.S. companies expose themselves to lawsuits "if they can no longer keep their promise to maintain the confidentiality of their customers' information?" the lawyers added.

The DOJ declined to comment on the hearing. In its case filings, the agency has argued that if Microsoft’s interpretation of the law is upheld, email providers could move content around the world in an effort to avoid law enforcement requests.

The U.S. Stored Communications Act and court rulings dating back several decades compel Microsoft to comply with the search warrant, the DOJ argued in a brief filed in March. "Microsoft’s argument is flatly contradicted by the explicit text of the statute, which requires service providers to disclose records when a warrant is obtained," the DOJ wrote.

Microsoft's opposition to the warrant has the company "fighting nearly 50 years of settled law," the DOJ's lawyers wrote. The company's "arguments crumble upon scrutiny."

Microsoft has gathered support from about two dozen other tech companies, including Amazon, Apple, AT&T, eBay and Verizon Communications, several digital rights groups and dozens of computer science professors.