Yes, I get that, but why?
To rephrase my original question: What was the original logic behind giving Presidents the power to pardon?
To balance out the judicial branch. The entire thinking behind the US system is to obtain a precarious balance between the powers of the judicial, executive and legislative branches of government. The founders were afraid of one branch being infiltrated and resulting in tyranny. The pardon power is part of that.
If the judiciary was infiltrated and a group managed to gain too much power in the courts, they might try to abuse their position by forcing lawmakers into making legislative decisions through threat of criminal persecution. The pardon power takes away that risk. Another point, made salient by President Washington is that justice at its best is also blind, and through the pardon power the president can take political and national security considerations into account. Washington's first pardon signalled that the pardon power should generally be used by the exectuive branch to strive to apply "tenderness and mercy on government" whenever possible.
The pardon power is not unlimited though, during the discussion of its implementation its limits was an important topic. In their view the threat to use the power to adhere to, give comfort and aid to an enemy of the USA, or cover up the president's own illegal activities by pardoning people he advised to comit crimes for him - could in itself be grounds for impeachment. Which is where the counter balance to pardons come in. The legislative branch can impeach a president for using, or even threatening to use, pardon powers to cover up crimes he himself is connected to. Hence the vagueness in the constitution
- fun fact; one article of impeachment against Andrew Johnson was the misdemeanor of speaking disrespectfully to congress.
