When will the federal government's "discretionary function" defense apply?

The court then adopted the three-prong test several circuit courts had used to determine when the defense applied, the requirements being: "(1) the United States approved reasonably precise specifications; (2) the equipment conformed to those specifications; and (3) the supplier warned the United States about the dangers in the use of the equipment that were known to the supplier but not to the United States." (Boyle , supra , 487 U.S. at p. 512, 108 S.Ct. 2510.) The first two requirements, said the court, insure "the suit is within the area where the policy of the discretionary function would be frustrated"that is, they insure "that the design feature in question was considered by a Government officer, and not merely by the contractor itself." (Ibid. ; see Jowers v. Lincoln Elec. Co. (5th Cir. 2010) 617 F.3d 346, 352354 [defense does not include a fourth, "significant conflict," requirement, as that is determined through the first two requirements].)