Merry christmas to my (admittedly sparse) readership.
The pardon system is fairly ridiculous, and has been abused on countless occasions, and is a fairly straight-forward affront to the rule of law. Richard Nixon pardoned scummy union leader Jimmy Hoffa. In 1974, Nixon himself was pardoned for his criminalization of the executive branch. Mark Felt, as we now know key to Nixon's downfall, was pardoned by Ronald Reagan for numerous abuses in pursuit of the Weather Underground (I have trouble seeing Felt's rule as noble. He exposed Nixon, but only because he was disgruntled for careerist reasons, Nixon had passed him over for head of the FBI.) Bill Clinton pardoned Marc Rich for 51 counts tax fraud and running illegal oil deals with Iran. As unedifying as these pardons are, the worst are those which allow the executive to cover-up its crimes: Bush I pardoning 6 Iran-Contra felons (Bush must have been knee deep in Iran-Contra) , Bush II pardoning "Scooter" Libby for obstruction of justice. Libby's actions saved Rove, and perhaps Cheney, from indictment.
Still, one thing we've never seen is a president retract a pardon. At least, not until now. The original pardon was pretty clearly outrageous, this person deserves to answer for what he's done. It's hard to say though, whether a president can really call off a pardon like that.