In Federalist No. 74, Alexander Hamilton explained the Constitution's grant to the President of the power to issue pardons:“The criminal code of every country partakes so much of necessary severity, that without an easy access to exceptions in favor of unfortunate guilt, justice would wear a countenance too sanguinary and cruel.”
The U.S. has both the world's highest incarceration rate, and the world's largest prison population. Yet President Obama has exercised the power to grant pardons more rarely than any president in modern history (according to a recent report by ProPublica.)
The power to show mercy was intended to be a central component in our criminal justice system. And it is needed today more than ever.