What is the test for 'discretionary exclusion' in a medical malpractice case?

This case must be reversed whatever rule is to be applied. Upon any theory it cannot be said at the pleading stage what type of functions respondents performed. Even an expert sometimes acts ministerially. The Attorney General conceded this at oral argument, stating that the surgeon who left a sponge in a wound after surgery would not be protected under the 'discretionary exclusion' rule. In sending this case back to the trial court, however, we deem it our obligation to direct the trial court as to what criteria it should apply and we have done so. We have followed the rule of Costley v. United States, supra (181 F.2d 723). ³