Capital felony murder statutes continue to enable states to sentence criminal defendants to death. These are often individuals who possessed no intent to kill and, in some cases, did not kill. These statutes remain constitutionally dubious under the basic principles of the Eighth Amendment, but the United States Supreme Court’s evolving standards of decency doctrine has proved an ineffective tool to remedy these injustices. This Article proposes a novel doctrinal approach by which the Court could promote more consistent sentencing outcomes in felony murder cases. Specifically, the Article argues for the adoption of a constitutional felony merger doctrine that “merges” the crimes of felony murder and first-degree murder in capital cases. Just as felony murder cannot serve as a tool by which prosecutors can convert second-degree assault killings into first-degree murders, felony murder should also not serve as a tool to convert noncapital crimes into capital ones. In Part I, the Article describes the use of capital felony murder and explains its constitutional infirmities under the Eighth Amendment. Part II explains the Supreme Court’s failed attempts to apply the Eighth Amendment to capital felony murder cases and why the Court’s doctrine remains an ineffective tool to remedy these injustices. In Part III, the Article proposes a new constitutional merger doctrine for capital felony murder cases. Finally, in Part IV, the Article makes the case for adopting a capital felony merger doctrine and explores its consequences.