In the McDonald v. Smith case of 1984, the U.S. Supreme Court ruled that there is no absolute immunity for defamatory statements made in a letter to the President. The petitioner, Bruce R. McDonald had written letters to then-President Reagan accusing respondent Robert L. Smith of bribery and conspiracy related to his appointment as United States Attorney for Western North Carolina District. When Smith sued him for defamation, McDonald claimed that he was protected by an absolute First Amendment privilege because his statements were part of a petition to government officials regarding matters of public concern. The court rejected this argument stating that while citizens have a right under the Petition Clause (First Amendment) to express their views on public issues and seek governmental redress without fear of retribution or punishment, it does not provide an absolute immunity from damages if they make false factual assertions which damage another's reputation. Thus, even though such petitions are generally given substantial protection against governmental interference under First Amendment rights; when it comes to private litigation over potential reputational harm caused by those petitions - like defamation suits - these protections aren't absolute but rather qualified ones subjecting them also towards state laws governing such torts.

In the dissenting opinion for McDonald v. Smith, Justice Brennan argued that the Petition Clause of the First Amendment should provide absolute immunity from liability for defamation to individuals who petition their government. He contended that this protection was necessary to ensure robust debate and criticism of public officials without fear of retribution or punishment. The majority's decision, he believed, undermined a fundamental aspect of democratic governance by chilling citizens' willingness to voice grievances against their government due to potential legal consequences. Furthermore, he disagreed with the majority’s view that there is no sound basis for granting greater constitutional protection to statements made in a petition than other expressions; instead asserting historical evidence supports such distinction.