The oral argument transcript from US vs Nixon (can the President refuse to turn over the tapes if subpoenaed? Decided 8-0 in the US' favo(u)r) is illustrative . . .
St. Clair is Nixon's attorney making the argument that conversations are confidential -- that the President shouldn't have to comply with a request to assist the investigation of a crime, like all Americans. As President, he is immune; the only way to remove him for crimes is impeachment.
I can't recall which judge is doing the questioning -- Thurgood Marshall, I think . . .
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MR. ST. CLAIR: if I may, an appointment of a judge, it's very important to the judiciary to have good judges. It's not at all unheard of for lawyers to be asked their opinion about a nominee. Now, if that lawyer wants to be sure that he’s going to be protected in giving candid opinions regarding a nominee for the bench, it’s absolutely essential that that be protected. Otherwise, you’re not going to get candid advice. Now this isn’t a State secret, it isn’t national defense? I suggest it's more important, because that judge may sit on that bench for thirty years.
QUESTION: Well, don't you think it would be important if the judge and the President were discussing how they were going to make appointments for money?
MR. ST, CLAIR: I'm sorry, sir, I didn’t understand your question.
QUESTION: Don't you think it would be important in a hypothetical case if an about-to-be-appointed judge was making a deal with the President for money?
MR. ST. CLAIR: Absolutely.
QUESTION: But under your [case] it couldn’t be. In public interest you couldn't release that.
MR. ST. CLAIR: I would think that that could not be released. if it were a confidential communication. If the President did appoint such an individual, the remedy is clear, the remedy is he should be impeached.
QUESTION: How are you going to impeach him if you don't know about it?
MR. ST. CLAIR: Well, if you know about it, then you can state the case. If you don't, know about it, you don't have it.
QUESTION: So there you are. You're on the prongs of a dilemma, huh?
MR. ST. CLAIR: No, I don't think so.
QUESTION: If you know the President is doing something wrong, you can impeach him; but the only way you can find out is this way; you can't impeach him, so you don't impeach him. You lose me some place along there.
{Laughter}
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The President can't just "do what he wants." The law/precedent is very clear.