Abstract: In this article, we revisit our 1995 analysis of the U.S. Supreme Court’s death penalty jurisprudence (Sober Second Thoughts: Reflections on Two Decades of Constitutional Regulation of Capital Punishment, 109 Harv. L. Rev. 357) in light of the steep decline in death sentences and executions over the past decade. Our consideration of the causes of this precipitous and unexpected turnaround leads us to the surprising conclusion that the same regulatory reforms of the modern (post-1976) era that we earlier described as legitimating and entrenching the practice of capital punishment have also contributed to its recent destabilization. We contrast the effects of the death penalty reforms of prior generations – such as narrowing the scope of death-eligible crimes, making death sentences discretionary rather than mandatory, privatizing and centralizing executions, and improving execution methods – with the reforms of the modern era of constitutional regulation. The reforms of the modern era have vastly increased the regulation and cost of the death penalty, required the professionalization of the capital litigation bar, led to lengthy periods of time between sentencing and execution, increased the focus on mitigation in capital trials, and contributed to the proliferation of life-without-parole as an alternative to the death sentence. We argue that the current regime represents a fundamental break with past modes of regulating capital punishment in ways that render the current American death penalty unstable, indeed precarious. We explore the implications of these insights for two broader debates – the first about the relationship between reform and abolition, and the second about the causes of American “exceptionalism” with regard to capital punishment.