There are of course loopholes big enough to drive a bus through. The biggest one being that if the feds are working with local or state police, this policy doesn't apply.
http://arstechnica.com/tech-policy/2015/09/fbi-dea-and-others-will-now-have-to-get-a-warrant-to-use-stingrays/The Department of Justice (DOJ) announced sweeping new rules Thursday concerning the use of cell-site simulators, often called stingrays, mandating that federal agents must now obtain a warrant in most circumstances. The policy, which takes effect immediately, applies to its agencies, including the FBI, the Bureau of Alcohol, Tobacco and Firearms (ATF), the Drug Enforcement Administration, and the United States Marshals Service, among others. "Cell-site simulator technology has been instrumental in aiding law enforcement in a broad array of investigations, including kidnappings, fugitive investigations and complicated narcotics cases," Deputy Attorney General Sally Quillian Yates said in a statement. "This new policy ensures our protocols for this technology are consistent, well-managed and respectful of individuals’ privacy and civil liberties."
