In the 1895 case of Spalding v. Vilas, the United States Supreme Court ruled that federal officials are immune from civil liability for actions taken in their official capacity, even if those actions later turn out to be unlawful or abusive. The case involved a dispute between a private citizen and Postmaster General John M. Vilas over alleged defamation by Vilas during an investigation into mail fraud schemes. The court held that high-ranking government officials like Vilas should not fear personal financial loss due to lawsuits when they perform their duties with discretion and judgment as long as they act within the scope of their authority without malice or corruption. The decision established what is now known as "qualified immunity," which protects public officials from being sued for discretionary actions performed within their official capacity unless they violated "clearly established" law at the time.

In the dissenting opinion for Spalding v. Vilas, Justice Harlan argued that government officials should not be granted absolute immunity from civil lawsuits related to their official duties. He maintained that such a broad protection could potentially lead to abuses of power and violations of citizens' rights without any legal recourse. Instead, he proposed a more limited form of immunity which would protect officials only when they acted in good faith and with probable cause. This approach, according to him, would strike a better balance between protecting public servants from frivolous lawsuits and ensuring accountability for misconduct or negligence in office.