This review focuses on empirical research about contemporary challenges to the death penalty in the United States. Challenges are factors that obstruct capital punishment, including legal or political restrictions; elimination at the federal or state level; or the hindrance of the process at its operational stages of charging, adjudicating, appeals, clemency, or executions. By the best-known measures, the death penalty has been in decline in the United States since the turn of the century. Lethal injection errors—“botches”—are arguably the most important current challenge to the institution. Wrongful capital conviction has made capital punishment less tolerable to the general public. Mitigation remains an important challenge to the death penalty. This review emphasizes botches, innocence, and mitigation but also touches on disparate impact, failure-to-deliver a social benefit, and cost. Along the way, this review proposes a framework for considering challenges as they occur on two continua of impact, a micro/meso/macro axis and a narrow/wide axis.