After the United States Congress passed the CLOUD Act, and the United States Justice Department dropped its previous request for a search warrant, the United States Supreme Court delivered a three page unsigned opinion declaring the Microsoft case moot. The Justice Department went back to court, and based on the new law, got a new search warrant to replace the one it originally got in 2013. Microsoft then promptly turned over the requested emails.
Since the government dropped its original request for a search warrant, the Supreme Court declared there was no longer a "live dispute" on the legal question the justices were asked to review. The court vacated the original Second Circuit Court ruling, and sent the case back to that court with instructions to vacate the original district court ruling against Microsoft, and to order the district court to dismiss the case as moot.
Microsoft's compliance with the new search warrant is not surprising given its support for the CLOUD Act.
How the CLOUD act meshes with the new European privacy laws that go into effect next month is unknown.