Donald Trump's lawyer William Consovoy just claimed that
a sitting president cannot be investigated even if he were to shoot someone on 5th Avenue.
It should be noted that there is no precedent for this position. Even the OLC opinion only forbids indictments, not investigations:
A federal appeals panel on Wednesday expressed skepticism that President Trump had a right to block state prosecutors in Manhattan from enforcing a subpoena that sought his personal and corporate tax returns for the last eight years.
The judges on a three-member panel in Manhattan peppered a lawyer for Mr. Trump with questions, expressing skepticism about the president’s argument that he was immune from criminal investigation. A lower court judge earlier this month rejected Mr. Trump’s claim, which has not previously been tested in the courts.
Carey R. Dunne, the Manhattan district attorney’s general counsel, cited the president’s famous claim that he could shoot someone on Fifth Avenue without losing political support.
Mr. Dunne asked what would happen in that extreme scenario? “Would we have to wait for an impeachment proceeding to be initiated?” he said.
Later, Judge Denny Chin posed the Fifth Avenue hypothetical to William S. Consovoy, a lawyer for Mr. Trump, and asked for his view.
“Local authorities couldn’t investigate? They couldn’t do anything about it?” Judge Chin asked, adding: “Nothing could be done? That’s your position?”
“That is correct. That is correct,” Mr. Consovoy said.
So, in the aforementioned hypothetical, they could not collect the gun, or look at the ballistics on the bullet, or collect surveillance video from the area according to Trump's lawyer.
Mr. Vance’s office in late August subpoenaed Mr. Trump’s accounting firm, Mazars USA, for his personal and corporate tax returns dating to 2011.
The district attorney had been investigating whether any New York State laws were broken when Mr. Trump and his company, the Trump Organization, reimbursed Michael D. Cohen, the president’s former lawyer and fixer, for payments he made to the pornographic film actress Stormy Daniels, who had said she had an affair with Mr. Trump.
………
Mr. Trump went into federal court last month, trying to block the district attorney’s subpoena. The president argued that the Constitution prevented a sitting president from being “investigated, indicted or otherwise subjected to criminal process.”
It should be noted that the OLC opinion is only binding on the US Department of Justice, not state prosecutors, and it;s argument had nothing to do with the constitution, they claimed that an indictment would be too disruptive to government.
Even if there were a separation of powers argument, that would not apply to state courts, and it would not apply to investigations.
Rather unsurprisingly, Robert Bork (×™ִמַּ×— שְׁמוֹ) was at the center of this 1973 memo, and it illustrates the utter moral and constitutional bankruptcy of the concept of the "Unitary Executive".
It should be noted that this opinion ignored a very clear precedent, the
arrest of Ulysses S. Grant for speeding and driving recklessly in 1872, but Bork and his ilk were never one to allow precedent, or the law, or the actual text of the Constitution, inform their arguments.