would have known.” Harlow v. Fitzgerald, 457 U.S. 800, 818, 102 S.Ct. 2727, 73 L.Ed.2d 396 (1982). The “contours of the right must be sufficiently dear that a reasonable official would understand what he is doing violates that right.” Anderson, 483 U.S. at 640, 107 S.Ct. 3034. In other words, the government official’s action in question need not have previously been found to be unlawful, see id.; rather, “in light of pre-existing law the unlawfulness must be apparent,” id. At the time of Shingleton and Collins’ actions in 1982, our case law clearly established that a defendant’s due process rights were violated when the police concealed material exculpatory evidence. See Barbee v. Warden, 331 F.2d 842, 846 (4th Cir.1964); see also Boone v. Paderick, 541 F.2d 447, 450-51 (4th Cir.1976) (<HOLDING>). As we noted in Barbee: Failure of the police
holding prosecutor has affirmative duty to disclose material exculpatory evidence holding that duty to disclose not neutralized because evidence was in the hands of the police rather than the prosecutor holding prosecutor had no brady duty to disclose that a certain witness could not positively identify the defendant holding the government has an affirmative duty to disclose exculpatory evidence to a criminal defendant holding that a conviction violated due process because the prosecutor knowingly refused to disclose crucial exculpatory evidence to the defendant