No doubt any federal indictment would be met with an effort to dismiss the charges on the grounds that Trump was pardoned. Trump’s attorneys would no doubt raise this claim at the earliest opportunity. I suspect this claim would be met with skepticism, however, as it would contradict the longstanding and well-established view of the Justice Department. While OLC opinions are not binding on federal courts, they are taken seriously, and particularly so where (as here) they run counter the executive branch’s interests. OLC opinions typically embrace robust conceptions of executive power. Thus an OLC opinion counseling restraint is more notable, and is likely to get extra consideration as a result. [As an aside, it is still possible that OLC could reverse its position between now and January 20. Were that to occur, I suspect any resulting memo would be recognized as a last ditch effort to shore up the President’s position, and not a neutral, dispassionate analysis worthy of judicial respect, but that could depend on what any such memo says.]
This is a long way of saying that if Trump tries to pardon himself, he could have a hard time making the pardon stick. It is certainly possible the Justice Department may have no interest in pursuing the former President, whether because it concludes there are no offenses worth pursuing, a sense of political comity, or a prudential judgment that state courts should get the first shot. But should there be such a prosecution, I doubt a self-pardon will offer ex-President Trump much protection in federal court.