Every time a case with an innocent starts winding through, the government drops the case, after having caused much grief to the innocent in question, rather than risk having their surveillance powers curtailed.
There is no known program to monitor in real time the position of every citizen - right now all of the data the government uses is incidental to the voluntary use of another service. I don't take much issue with the service generating that data - but in no case should it be considered commoditizable nor should the government be able to access it on a whim for whatever purpose the government sees fit.
Right now the process is working as defined, the law exists to constrain abuses, and to a lesser extent prevent them - but the presumption of the founders was that government will always try to take the maximum amount of power it can, and that the courts exist largely to strike the balance.