I am pretty sure that they were referring to the 4th amendment (from Wikipedia):
"The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."
Now I'm a Libertarian, and I read that as: "If you don't have a fucking warrant, then you don't get to collect SHIT. No metadata, no *actual* data, no GPS data, nothing. It is real simple, if you are trying to build a case against me, then you had better have a warrant to collect ANY data (at least that is the way it should be). In reality, there is no constitution any more -- it is just a faded memory.