[barnabee]

Really a warrant should be required to carry out any kind of in-depth, prolonged, or otherwise invasive surveillance or investigation into someone.

It’s not just which data or where they get it (though surely many types and sources of data should be restricted too, especially without a warrant) but the fact that they are building a profile, targeting, etc. at all. These are things the government/law enforcement should not be doing lightly or without supervision.