Apple was subpoenaed to fork over Congressmen and staff records in a media leak investigation2
This happened in May, even though the grand jury subpoenas had been issued in February 2018 under a gag order, as part of a DoJ investigation into unauthorized leaks of classified information to the media, reports the New York Times.
At the time, the Russiagate was in full swing, as well as the revelations of the former FBI Director James Comey, and, as has become customary in Washington, self-serving leaks kept popping up in various media outlets with the usual preface "sources from the intelligence community."
Both sides of the aisle are guilty of that, plus intelligence sources are often themselves leaking information with their own purposes, but the DoJ at the time decided to investigate, casting a wide net for more than a 100 Apple accounts, some of which had little to do with the issue.
Needless to say, those who were notified by Apple it had to turn over their records, like House Intelligence Committee Chairman Adam Schiff, were less than happy about it, and now demand answers and an explanation.
What exactly did Apple turn over to the DoJ while complying with the subpoena, though? Metadata, actually, as well as account information, not emails, photos, or actual message content, just the minimum it is required to reveal by law, if that's of any comfort to those that were on the receiving end of the subpoenas.