The Federal Tort Claims Act [FTCA] is a statute enacted by the U.S. Congress, which partially waives "sovereign immunity".
Under 28 U.S.C.§1346(b), government liability is limited to "circumstances where the United States, if a private person, would be liable to the claimant in accordance with the law of the place where the act or omission occurred". However, the FTCA exempts claims based upon the performance, or failure to perform, a "discretionary function or duty".
There has been much litigation over the difficulty parsing the words "discretionary function or duty". What is discretionary? Several blog entries will follow this one, and partially describe the tortured legal history of "discretionary function or duty".