The NSA secured an order from the FISC directing Verizon to turn over metadata on all calls made within the US, which includes data about the ___location of their customers' mobile phones. The Supreme Court has ruled that long-term tracking requires a warrant. The decision was unanimous, but split as to reasoning. The majority held that such tracking without a warrant violates the 4th amendment. It is quite likely that obtaining phone records for the purpose of tracking ___location has the same legal status.