There is no case that establishes absolute immunity for communications between a President and advisors!
There is in fact only one case regarding Executive Privilege that's been heard by the Supreme Court and that is United States vs. Nixon and in that ruling they stated that there was no such thing as absolute immunity. It is a "qualified privilege" that can be lost if the courts are seeking subpoenaed materials in a criminal case!
"1. The Supreme Court and executive privilege
As the 2014 CRS study explained, āthe Supreme Court has never addressed executive privilege in the face of a congressional demand for information.ā Instead, the case in which the court first recognized such a privilegeā
Nixonāarose from a subpoena issued by Special Prosecutor Leon Jaworski as part of his investigation into the Watergate break-in. But the courtās 8-0 ruling in
Nixon nevertheless provides three important benchmarks for executive privilege vis-Ć -vis Congress today.
First, emphasizing āthe valid need for protection of communications between high Government officials and those who advise and assist them in the performance of their manifold duties,ā the
Nixon court traced executive privilege not to the common law, but to Article II of the Constitution. As Chief Justice Warren Burger wrote, ā[w]hatever the nature of the privilege of confidentiality of Presidential communications in the exercise of Art[icle] II powers, the privilege can be said to derive from the supremacy of each branch within its own assigned area of constitutional duties.ā In other words, āthe protection of the confidentiality of Presidential communications has ⦠constitutional underpinnings,ā meaning that the privilege cannot be abrogated by statute. Indeed, even though President Richard Nixon ultimately lost before the court, this part of the courtās decision was a significant (and, given the result, unnecessary) win for the presidency.
Second, the
Nixon court rejected the presidentās claim that such a privilege is absolute, emphasizing that āthe impediment that an absolute, unqualified privilege would place in the way of the primary constitutional duty of the Judicial Branch to do justice in criminal prosecutions would plainly conflict with the function of the courts under Art[icle] III.ā Instead, the court held that the executive privilege protected by Article II is a qualified privilege, and concluded that āit is necessary to resolve [the] competing interestsā between executive privilege and the role of the courts āin a manner that preserves the essential functions of each branch.ā
Third,
Nixon held that the presidentās interest in the confidentiality of his own communications, as memorialized in the tapes sought by the subpoena, was outweighed by āour historic commitment to the rule of law.ā In
Nixon, specifically, āwhen the ground for asserting privilege as to subpoenaed materials sought for use in a criminal trial is based only on the generalized interest in confidentiality, it cannot prevail over the fundamental demands of due process of law in the fair administration of criminal justice.ā And as the court would explain three years later in
another case involving Nixon, the privilege recognized in the earlier 1974
Nixon ruling āis limited to communications āin performance of (a Presidentās) responsibilities ⦠of his office,ā and made āin the process of shaping policies and making decisions.āā
Executive privilege, Congressā subpoena power, and the courts: A brief overview of a complex topic - SCOTUSblog