What is the test for a government official to be held liable in negligence in a civil case?

Government officials performing discretionary functions are generally shielded from liability so long as their conduct "does not violate clearly established statutory or constitutional rights of which a reasonable person would have known." Harlow v. Fitzgerald, 457 U.S. 800, 818, 102 S.Ct. 2727, 2738, 73 L.Ed.2d 396 (1982). In addition, the defendant must know more than just that a generalized constitutional right exists; rather, "[t]he contours of the right must be sufficiently clear that a reasonable official would understand that what he is doing violates that right." Anderson v. Creighton, 483 U.S. 635, 640, 107 S.Ct. 3034, 3039, 97 L.Ed.2d 523 (1987). "[I]n the light of pre-existing law the unlawfulness must be apparent." Id.