The ISPs also challenged the government's breezy assumption that separating the data from the (equally revealing) metadata would be simple, not least because an Internet connection is typically being used for multiple services simultaneously, with data packets mixed together in a completely contingent way.
Hare described a typical usage scenario for a teenager on their computer at home, where they are playing a game communicating with their friends using Steam; they are broadcasting the game using Twitch; and they may also be making a voice call at the same time too. "All those applications are running simultaneously," Hare said. "They are different applications using different servers with different services and different protocols. They are all running concurrently on that one machine."
Even accessing a Web page is much more complicated than the government seems to believe, Hare pointed out. "As a webpage is loading, you will see that that webpage is made up of tens, or many tens, of individual sessions that have been created across the Internet just to load a single webpage. Bluntly, if you want to find out what someone is doing you need to be tracking all of that data all the time."