"Feds Warrantlessly Tracking Americans’ Credit Cards in Real Time"

This article, called "Hogwatch" (I wonder if that relates to their spending habits or the subjects), details how agencies can write up their own subpoena, etc.,

• The document, obtained by security researcher Christopher Soghoian, explains how so-called “Hotwatch” orders allow for real-time tracking of individuals in a criminal investigation via credit card companies, rental car agencies, calling cards, and even grocery store loyalty programs.
• For credit cards, agents can get real-time information on a person’s purchases by writing their own subpoena, followed up by a order from a judge that the surveillance not be disclosed. Agents can also go the traditional route — going to a judge, proving probable cause and getting a search warrant — which means the target will eventually be notified they were spied on.
• But the Justice Department does not report or make public the number of times it got real time or historic cell phone location information, nor how often it is using these so-called “hotwatch” orders.