Some people are under the impression that this has just begun recently [lol]
I was first trained to locate, identify, and counter Electronic Eavesdropping Measures over 10 years ago. When I was first trained and assigned, I was amazed by how many "bugs" marked [b]JSI Telecom [/b] that we found planted in agency offices. (JSI Telecom has only one customer, and it's LEO) On my own research I found that over 90% of the electronic anomalies we found; slaves, leaches, DNR's, carrier current units both RF and hard-wired, were placed there [u]without a warrant[/u]. Of course, when found these units would be disavowed or identified as "investigative tools". (Investigaive Tool means that the bug was put into place [i]illegally[/i] and anything found with it would be inadmissable in a court of law, but then all you had to do was develop PC and convince a judge to issue you a Title III warrant for it after-the-fact. The single biggest abusers were probably BATF, followed by DEA and then FBI (yes, FBI; they had a real appetite for DNR's (Dialed Number Recorders) placed on a suspect's phone line. It's a dirt little secret tool that allows you to monitor the phone numbers of all incoming and outgoing calls from a suspect's phone number [u]without[/u] actually listening to or recording the phone call. From this, you develop Probable Cause and get a warrant for the tap. Also, there was an unreal number of taps placed on other rival agencies by other rival agencies to find out where their budgets were going to collide, (Spy vs Spy?), because "I'll be damned if we're going to loose our funding for project X just because another agency has a similar program already in place. We also often ran into interagency refusal to share information, (you can teach another gov't agency a life-saving technique, but you CANNOT teach them OUR way of doing this because our way is "Classified", even if it would save lives)
We even once found a bug in a full-bird Colonel's apartment that had been put there by ANOTHER officer's WIFE just so she could get in on some gossip that she had been left out of the circle. (Why are there TWO baby monitors here and just one receiver? Because the bitch kept the other receiver and is listening to it RIGHT NOW, stupid!)
In summary, most of these abuses, whether it's illegal wiretaps, unauthorized access of bank records, library cards, ad nauseum, this shit has been going on a LONG time before now.