The EFF has put together information pertaining you, your data, and law enforcement. As more and more people come to rely on electronic data for record keeping and communication not too many concern themselves with where their bits and bytes come and go.  
This is a good introduction to where we are in the State of 1984, where cameras track out movements in public places and our data is sifted through for reasons other than our own.  
Good reading for the paranoid and not so paranoid.