The US Supreme Court agreed on Monday to review the Microsoft Ireland case.
The case began in December 2013, when US government agents, as part of an investigation into a narcotics case, served a warrant pursuant to the Electronic Communications Privacy Act for emails associated with a particular user account.
While Microsoft did provide account information that it held on its US servers, it refused to provide the data held on a server based in the Republic of Ireland.
This refusal was on the basis that the data was located in the Republic of Ireland and so a request for the non-US based data would need to made to the Irish authorities under the Mutual Legal Assistance Treaty.
The US government fought back, noting that Microsoft could access the data from Redmond, Washington, which made this a territorial search, not an extraterritorial one. The lower courts agreed with the US Department of Justice, at which point Microsoft headed to the US Court of Appeals for the Second Circuit, where it won.
Microsoft and other interested parties have pointed to the fact that the key issue here is that the Electronic Communications Privacy Act is outdated legislation and Congress needs to address this urgently and enact new legislation, such as the International Communications Privacy Act (ICPA) of 2017.