The article -- Federal Tort Claims & The Issue Of Sovereign Immunity, California Lawyer Website, June 22, 2016 can be read here: http://www.callawyer.com/2016/06/ftca-and-the-limits-of-sovereign-immunity/.
The article discusses the 9th Circuit' recent May 20, 2016 Opinion in Edison v. United States, ___ F.3d ___ (9th Cir. 2016), 2016 WL 2946347 (9th Cir.), where the Court enumerated the limits on the application of the "independent contractor" exception in cases where the USA has hired subcontractors to perform governmental duties but retained some responsibilities.