In Carpenter v. United States, the Court by a 5-4 (Roberts with the 4 libs) overturned the conviction of a man who was connected to the scene of a robbery by the warrantless search (subpoena) of his cell phone records from his provider.
Although I agree with the result, I think Gorsuch has the best legal view of it. The majority test is uncertain and the results for others down the road is unclear.