The Constitution provides the Chief Executive with the ultimate power to pardon. Governors have similar powers in state matters. It was supposed to be a safety valve, an opportunity for society to temper its punishments or right wrongs, derived from the absolute power of the sovereign.
Bush 41 had a lackluster Presidency, Clinton 42's was excellent. But, long before they shared the world's stage as the world's disaster-highlighters-in-chief, they shared the shameful practice of 11th hour pardons, demonstrating the cynical use to which the pardon power could be exercised on behalf of political cronies.
Today, because of the pardon power exercised at the 11th hour by Bush 41, a convicted neocon felon, Elliott Abrams (no relation, less DNA homology than with a chimp) essentially runs Bush 43's policy on Israel and Palestine. Instead of pacing up and down a jail cell, this felon trods the back corridors of the State Department as a major barrier to the United States taking an active, positive role in bringing a half-century of war, killings, dislocation and misery to an end. In the early days of the recent Israel-Lebanon War, he told the Israelis they had a free hand to attack Syria. Caspar Weinberger was allowed to steal from historians the truth about Iran-Contra, burying Bush 41's role while Reagan's VP at the same time.
Also at the 11th hour of his Presidency, Clinton 42 suddenly found it compelling to issue a pardon to Mark Rich, a financial crook who had escaped with his millions without serving any time, or paying any penalty. Like other white collar criminals, Rich had tried to burnish his image with charitable contributions, and, through his non-criminal wife, did not omit the Clinton campaigns from his largesse. Indeed, in an irony that could only occur because of the interbreeding that occurs within the Beltway, Clinton's most egregious pardon came at the behest of Scooter Libby himself.
There is a remedy, that does not remove the pardon power, or otherwise burden it with imposed rules that require adjudication, but also makes the "pardoner" (aka, the decider) accountable: pass a quick Constitutional Amendment that restricts the pardon power to February through August in any year. For the other months, the President has no such power. That would require the President to issue pardons prior to an election, so the electorate can hold him or his party accountable at the polls, and prevent the 11th hour pardons for which there is only the accountability of history.
Congress could pass such a simple Amendment within a week, and send it to the State legislatures where, one would suspect, it would also pass easily. Moreover, it would be more than interesting to learn just who is opposing or blocking such a simple proposition.