I addressed this concern, particularly as it relates to a provision of the Patriot Act, in my article "The Patriot Act and the Quiet Death of the US Bill of Rights". In it I wrote, "In other words, the precedent set by the Patriot Act appears to be serving to accelerate the rapid disintegration of civil liberties in this country.
The fact that in 2009 Sprint disclosed that law enforcement made 8 million requests in 2008 alone for its customer’s cell phone GPS data for purposes of locational tracking should only add to these legitimate privacy concerns
And that's not all. Back in 2009, the Washington Post reported that while serving as a U.S. attorney during the Bush administration, Christopher Christie tracked the whereabouts of citizens through their cell phones without warrants. The ACLU obtained these documents from the Justice Department in an ongoing lawsuit over cell phone tracking. While the documents reveal 79 such cases on or after Sept. 12, 2001, they do not specify how many of the applications were made during Christie's tenure.
Tracking without a warrant disregards an internal U.S. Justice Department recommendation that prosecutors obtain probable cause warrants before gathering location data from cell phones. Of the cases in which probable cause wasn't established, documents showed 19 allowed the most precise tracking available. Those cases occurred after the November 2007 Justice Department recommendation that prosecutors seek warrants.