The IRS filed a motion in federal court to force Coinbase hand over all of their customer's personal records in response and accordance with the “John Doe” summons the agency filed back in November of 2016..
Coinbase stated on their blog:
Our legal team is in the process of reviewing the IRS’s motion. We will continue to work with the IRS to assess the government’s willingness to fundamentally reconsider the focus and scope of the summons. If it does not, we anticipate filing opposition papers in court in coming months. We will continue to keep our customers updated as to status.
In a nutshell the IRS wants all customer records without reason to do a discovery of the data to see if anyone did anything wrong, this includes years the IRS didn't even have a formal opinion on virtual currency.
It's beginning to look like this may go 12 rounds.