https://www.supremecourt.gov/opinions/23pdf/23-939_e2pg.pdf
> And he is entitled to at least presumptive immunity from prosecution for all his official acts.
> Testimony or private records of the President or his advisers probing such conduct may not be admitted as evidence at trial
> The Constitution does not tolerate such impediments to “the effective functioning of government” [as when] the possibility of an extended proceeding alone may render [the President] “unduly cautious in the discharge of his official duties.”
> The immunity the Court has recognized therefore extends to the “outer perimeter” of the President’s official responsibilities, covering actions so long as they are “not manifestly or palpably beyond [his] authority.”
> In dividing official from unofficial conduct, courts may not inquire into the President’s motives.
> Nor may courts deem an action unofficial merely because it allegedly violates a generally applicable law
> Enduring separation of powers principles guide our decision in this case
Supreme Court history has no broader grant of immunity based on principles less definitive.