Until they make THAT (switching off your phone for 1 or 2 cells and turning back on 1 or 2 cells over) a crime. And start compelling cellphone companies to provide them with the records of everyone who does that. And start targeting those people. Like structuring [0].

[0] http://www.nytimes.com/2014/10/26/us/law-lets-irs-seize-acco...