Due process? That shouldn’t require 15 or 20 years. Offing convicted murderers beats the hell out of feeding and housing them until they die of old age. The savings would be astronomical. How much do you think has been spent on assholes like Charles Manson? (And HE’S not even on death row.)
There are only 3300 inmates on death row in the US.
Out of 2 Million plus inmates.
Every study (mostly DNA studies) in the US shows something like a few percentage of death row inmates executed were innocent.