Why is it moral? For one reason, because we put too much faith in the law qua law.
In the United States, our civic religion is the Rule of Law—we have no monarchy, and we are less tribalist than more ethnically and religiously homogeneous nation-states. Instead the highest symbol of our nation is a legal document, with its own legalistic cult and rituals. To be sure, the rule of law is in many ways an ideal of rational order and equality without favoritism. But a spillover effect is the tendency to treat all legal codes as if they were handed down from Mount Sinai, no matter how unreasonable or cruel they may be.Why is it practical? I'll cite just one argument here, though you can read the rest if you like:
Devotion to the Rule of Law has an ugly side in resentment of executive acts of mercy, at the level of practice and high theory. Immanuel Kant, often thought of as a Birkenstock-wearing human-rights guy, was one of the most vicious retributivists in the history of moral philosophy, an implacable opponent of royal clemency. In 1764, Milanese philosophe Cesare Beccaria argued that the same crimes must carry the same punishment regardless of the perpetrator’s rank or station, no exceptions—a radical proposition for its time. This sounds unobjectionable, but this Enlightenment universalism has had harsh ramifications in the American context where, combined with Puritan moral panics and the authoritarian heritage of slavery and Jim Crow, it has frequently made for a justice system with a tendency to degrade and “level down” to an egalitarian level of misery....
At the founding of the country, executive power was seen not as a violation of our self-image as a “nation of laws not men” but as a necessary and healthily legitimate part of any popular government. As Hamilton wrote in Federalist 74: “the benign prerogative of pardoning should be as little as possible fettered.” Without pardon power, “justice would wear a countenance too sanguinary and cruel.” Justice John Marshall also upheld clemency as “an act of grace, proceeding from the power entrusted with the execution of the laws.”
Our incarcerated population is also aging rapidly, and though older prisoners have far lower recidivism rates, few states are availing themselves of geriatric release. For instance, Virginia in 2012 granted geriatric release to less than 1 percent of about 800 prisoners eligible, according to the state parole board. Meanwhile, as the Virginian Pilot reported, “during the same period, 84 inmates died in state prisons.” Running high-security nursing homes is neither compassionate nor fiscally sound—another reason to restore and expand clemency.That seems like a reasonable case to me. Some prisoners ought to die in prison simply because of the magnitude of their crimes -- Charles Manson, perhaps. Others really shouldn't be in prison, even if they were pretty hard-core thugs as young men, because they pose no threat that would justify paying for both guarding them and caring for them in their age.
What's being asked for here is not pardons by and large, but clemency. They would remain under the disabilities associated with being a convicted felon. We just wouldn't be responsible for them.