I have. The only think I have seen anyone refer to is Ford’s pardon of Nixon. In Ford’s speech he said....
“There are no historic or legal precedents to which I can turn in this matter, none that precisely fit the circumstances of a private citizen who has resigned the Presidency of the United States. But it is common knowledge that serious allegations and accusations hang like a sword over our former President’s head, threatening his health as he tries to reshape his life, a great part of which was spent in the service of this country and by the mandate of its people.”
http://watergate.info/1974/09/08/ford-pardons-nixon.html
Notice he said “There are no historic or legal precedents to which I can turn in this matter”. He only referenced Article II, Section 2 of the constitution....
“Now, therefore, I, Gerald R. Ford, President of the United States, pursuant to the pardon power conferred upon me by Article II, Section 2, of the Constitution, have granted and by these presents do grant a full, free, and absolute pardon”.
“Constitution, Article II, Section 2
The President shall be commander in chief of the Army and Navy of the United States, and of the militia of the several states, when called into the actual service of the United States; he may require the opinion, in writing, of the principal officer in each of the executive departments, upon any subject relating to the duties of their respective offices, and he shall have power to grant reprieves and pardons for offenses against the United States, except in cases of impeachment.
He shall have power, by and with the advice and consent of the Senate, to make treaties, provided two thirds of the Senators present concur; and he shall nominate, and by and with the advice and consent of the Senate, shall appoint ambassadors, other public ministers and consuls, judges of the Supreme Court, and all other officers of the United States, whose appointments are not herein otherwise provided for, and which shall be established by law: but the Congress may by law vest the appointment of such inferior officers, as they think proper, in the President alone, in the courts of law, or in the heads of departments.”
Doesn’t say anything about pardoning someone for things they haven’t been charged with. What Ford did was use a pretty broad brush and it was not challenged by law.
Please refer me to any other cases besides this one where a president pardoned someone when they haven’t been charged because my google is not bringing anything up.