In the case of Pottawattamie County, Iowa, et al. v. Curtis W. McGhee Jr., et al., 2009, two African-American men who were wrongfully convicted for murder and spent over 25 years in prison sued former prosecutors from Pottawattamie County on grounds that their constitutional rights had been violated by fabricated evidence during their trial. The defendants argued they were immune to lawsuits as prosecutors are generally protected under absolute immunity when acting within the scope of their prosecutorial duties. However, the plaintiffs contended this immunity should not extend to actions taken before a prosecutor's formal involvement in a case such as during an investigation phase where they acted more like police officers than attorneys preparing for litigation - roles usually only granted qualified immunity which can be overcome if official conduct violates clearly established constitutional rights.

In the dissenting opinion for Pottawattamie County, Iowa v. Curtis W. McGhee Jr., et al., Justice Scalia argued that prosecutors should be immune from lawsuits over their actions in judicial proceedings, even if they knowingly used false testimony to secure a conviction. He contended that this immunity is necessary to prevent an onslaught of claims against prosecutors and maintain the integrity of the legal system. The majority's decision, he believed, could deter competent individuals from becoming or remaining as prosecutors due to fear of personal liability for decisions made during trials - potentially undermining effective law enforcement and administration of justice.