Stingrays are a cell phone specific technology.  It interleaves itself between your cellphone and the cellphone towers & infrastructure.  Unfortunately, they're nearly impossible to detect for the vast majority of cell phone users.  About the only possible way to defeat their snooping is to use completely encrypted end to end connections, and even those are vulnerable to the classic man in the middle attack.

LE absolutely does not want details of their usage to get into public records.  There have been court cases where stingray data has been withdrawn rather than allow details to exist in court records. As a result of this, while LE does use them, they are being somewhat careful to not use them for something less than a high profile case.

http://www.scientificamerican.com/article/what-is-the-big-secret-surrounding-stingray-surveillance/

http://blog.tenthamendmentcenter.com/2014/05/new-law-minn-governor-signs-bill-to-ban-warrantless-cellphone-tracking/

Speaking of rights and freedom. I read a good book about the beginnings of the American revolution called '"46 pages, Thomas Paine, Common Sense, and the Turning Point to Independence, by Scott Liell.

 It's an easy read and it's a good refresher course of American revolution facts.