The case of Stephen Buckley v. Michael Fitzsimmons et al., 1992, revolved around the issue of prosecutorial immunity from civil lawsuits for actions taken during investigations before probable cause has been established. Stephen Buckley was wrongfully accused and charged with rape and murder based on false forensic evidence provided by prosecutors, including defendant Michael Fitzsimmons. After spending nearly three years in jail awaiting trial, all charges against him were dropped due to lack of evidence. Buckley then sued the prosecutors for violating his constitutional rights under the Fourth Amendment (unreasonable searches and seizures) and Fourteenth Amendment (due process). The Supreme Court ruled that while prosecutors are immune from being sued over their conduct in courtrooms, they do not have absolute immunity for their investigative work especially when it is done before establishing probable cause to arrest a suspect. Therefore, this decision allowed Buckley's lawsuit against the prosecutors to proceed.

In the dissenting opinion for the case of Stephen Buckley v. Michael Fitzsimmons et al., Justice Scalia argued that prosecutors should be granted absolute immunity from lawsuits related to their official duties, even when those actions occur during a criminal investigation rather than in court. He contended that this protection is necessary to prevent prosecutors from being deterred in performing their functions due to fear of potential litigation. The majority's decision, he believed, would lead to an increase in frivolous lawsuits against prosecutors and hinder them from effectively carrying out justice. Furthermore, he disagreed with the majority's distinction between investigative and advocacy roles of a prosecutor as it was not historically supported nor practically workable.