What is the purpose of pardoning powers?

Question

Various countries have pardoning powers given to either the president or the governor, this is secured as a constitutional right of the president and governor.
What is the purpose of such powers? Is there a special reason why are they handed to a president or governor?

Answer 1

They are the modern legacy of the Royal prerogative of mercy

Or in Commonwealth countries that still have a monarch, it is the Royal prerogative of mercy.

Its modern functional purpose is to provide justice beyond the law. Its historical purpose was to allow the monarch to commute automatic death sentences in a legal system that did not, at that time, have an appeals process to correct miscarriages of justice, either through mistake or in a system that was not as flexible as it is today.

It exists as the ultimate backstop against injustice. Ultimately, exercise of the power is a political rather than a judicial one and, as such, any limits on misuse come through the ballot box, not the court.

Answer 2

The purpose was to place in an individual person, independent from the judiciary, the power and individual agency to provide mercy for outcomes that have resulted in "unfortunate guilt." See generally, "The Constitution Annotated", and Federalist 74.

The US framers did not place the power in an individual simply for the reason that the "King is a single person." They did not inconsiderately replicate the U.K. approach. There was debate about whether the pardon power would be a step on path back to monarchy. There was debate about whether to include the legislature in the pardon power.

For one rationale for placing the power in an individual, see Federalist 74:

As the sense of responsibility is always strongest, in proportion as it is undivided, it may be inferred that a single man would be most ready to attend to the force of those motives which might plead for a mitigation of the rigor of the law, and least apt to yield to considerations which were calculated to shelter a fit object of its vengeance.

Answer 3

Under the rule of law, laws must not be retroactive and they should not be too specific. But sometimes, justice requires not applying the existing law in a specific case. By giving the power of pardon to the executive, and not the legislative or judiciary, there is no suggestion that a pardon creates a new law or judiciary precedent. It stands aside.