Microsoft v. Justice Department
It's not just Apple and the FBI. The linked article states, "In its complaint, Microsoft says the Electronic Communications Privacy Act, which dates to 1986, lets courts order companies not to inform customers whose email or other private information is being sought by the government."
It will be interesting on how this all unfolds given Apple's confrontation with the FBI.
(via NPR) Microsoft Sues Justice Dept., Seeking To Inform Customers About Seized Data: http://www.npr.org/sections/thetwo-way/2016/04/14/474252772/microsoft-sues-justice-dept-seeking-to-inform-customers-about-seized-data