Not sure about that. From the Heritage guide to the constitution -
"The scope of the pardon power remains quite broad, almost plenary. As Justice Stephen Field wrote in Ex parte Garland (1867), "If granted before conviction, it prevents any of the penalties and disabilities consequent upon conviction from attaching [thereto]; if granted after conviction, it removes the penalties and disabilities, and restores him to all his civil rights; it makes him, as it were, a new man, and gives him a new credit and capacity....A pardon reaches both the punishment prescribed for the offence and the guilt of the offender....so that in the eye of the law the offender is as innocent as if he had never committed the offence." A pardon is valid whether accepted or not, because its purposes are primarily public. It is an official act. According to United States v. Klein (1871), Congress cannot limit the President's grant of an amnesty or pardon, but it can grant other or further amnesties itself. Though pardons have been litigated, the Court has consistently refused to limit the President's discretion. Chief Justice Warren E. Burger, however, in Schick v. Reed (1974), seemed to limit the Court's restraint to pardons under "conditions which do not in themselves offend the Constitution.""
Yes there is an argument to be made whether pardons can be made in advance.
It doesn’t make sense to do it in advance imo. If pardons can be made in advance why have laws? Can 0bama simply pardon everyone right now ... and it would be over?