This is roughly in line with my position on the topic, which is that I don't have a problem with capital punishment in the abstract, but in its day-to-day application (outside truly exceptional circumstances) I have no confidence in how it is carried out. I think it is pretty clear that the constitution contemplates capital punishment, and there isn't any particularly strong grounds to label it "cruel and unusual" as an abstract matter -- but as applied in this country it simply is not working in a way consistent with our ethical and constitutional commitments.
A study commissioned by the institute said that decades of experience have proved that the system cannot reconcile the twin goals of individualized decisions about who should be executed and systemic fairness. It added that capital punishment is plagued by racial disparities; is enormously expensive even as many defense lawyers are underpaid and some are incompetent; risks executing innocent people; and is undermined by the politics that come with judicial elections.
So yeah, that.