How the Death Penalty Works: Eligibility, Appeals, Methods, and Constitutional Issues

The Death Penalty in the United States Today

Capital punishment is authorized by the federal government and by 27 U.S. states as of 2026. The remaining 23 states and the District of Columbia have abolished it, either by legislation or by judicial decision. Even in states that retain the death penalty, its use has declined dramatically: the number of executions carried out annually peaked at 98 in 1999 and has fallen to fewer than 25 in most recent years. The vast majority of death sentences are never carried out — most are reversed on appeal or commuted by executive clemency.

The modern era of American capital punishment began after the Supreme Court struck down existing death penalty statutes in Furman v. Georgia (1972) on the grounds that their arbitrary application constituted cruel and unusual punishment under the Eighth Amendment. Four years later, in Gregg v. Georgia (1976), the Court upheld revised Georgia statutes that provided guided discretion through bifurcated proceedings — separate guilt and sentencing phases — and required mandatory appellate review. Most states subsequently restructured their statutes to conform to the Gregg framework.

Crimes Eligible for the Death Penalty

In the United States, the death penalty is constitutionally limited to crimes involving the taking of life. In Coker v. Georgia (1977), the Supreme Court held that the death penalty is disproportionate punishment for the rape of an adult woman when the victim was not killed. In Kennedy v. Louisiana (2008), the Court extended this holding to bar the death penalty for child rape that does not result in death, reasoning that death is categorically disproportionate to non-homicide crimes against individuals.

At the federal level, more than 60 offenses are theoretically capital, including first-degree murder, espionage, treason, and drug trafficking resulting in death. In practice, federal death sentences are reserved for first-degree murder accompanied by specified aggravating factors. State capital statutes typically define capital murder as first-degree murder committed with one or more statutory aggravating factors — such as murder for hire, multiple victims, murder of a law enforcement officer, murder during the commission of another felony (felony murder), or murder of a particularly vulnerable victim such as a child.

The Sentencing Process: Aggravating and Mitigating Factors

Under the guided discretion framework required by Gregg, the sentencing phase of a capital trial is separate from the guilt phase. After a guilty verdict, both prosecution and defense present evidence relevant to whether the defendant should be sentenced to death or life imprisonment. Juries must weigh aggravating factors (statutory circumstances that make the crime worse, such as torture or prior violent convictions) against mitigating factors (circumstances that argue for a lesser sentence, such as intellectual disability, traumatic childhood, mental illness, or lack of prior criminal history).

The Supreme Court has established categorical bars on the death penalty for certain categories of defendants. In Atkins v. Virginia (2002), the Court held that executing individuals with intellectual disability violates the Eighth Amendment. In Roper v. Simmons (2005), the Court barred the execution of individuals who were under 18 at the time of the crime.

The Appeals Process

Capital cases are subject to an extensive and multi-layered appellate process that can take decades to exhaust. After sentencing, defendants pursue direct appeal to the state's intermediate appellate court and then to the state supreme court, challenging legal errors at trial. Most states mandate review of all death sentences regardless of whether errors were raised at trial.

Following the direct appeal, defendants pursue state post-conviction review (also called state habeas corpus), where they can raise claims of ineffective assistance of counsel, newly discovered evidence, and constitutional violations not apparent from the trial record. If state remedies are exhausted, defendants petition for federal habeas corpus review in the federal district courts, and can appeal adverse decisions through the federal circuit courts to the Supreme Court.

The Antiterrorism and Effective Death Penalty Act of 1996 (AEDPA) imposed significant restrictions on federal habeas review, requiring deference to state court decisions unless they involved an unreasonable application of clearly established federal law, and imposing a one-year statute of limitations on federal petitions. Critics argue these restrictions have made it more difficult to correct wrongful convictions and constitutional violations in capital cases.

Methods of Execution

Lethal injection is the primary method of execution in the United States, used by all executing states and the federal government. The standard three-drug protocol uses a sedative (typically midazolam or sodium thiopental) to render the inmate unconscious, a paralytic (such as pancuronium bromide) to stop breathing, and potassium chloride to stop the heart. Significant controversy surrounds the method, as pharmaceutical companies have refused to supply drugs for executions and legal challenges have proliferated based on the risk of pain if the sedative does not work properly.

Other methods authorized as alternatives in some states include electrocution, nitrogen gas hypoxia (authorized in several states as an alternative to lethal injection and used in Alabama and Oklahoma), lethal gas (using other agents), hanging, and firing squad (authorized in several states). No state currently uses these as primary methods, though several have authorized them as backups when lethal injection is unavailable.

Cost, Deterrence, and Constitutional Debates

Studies consistently find that capital cases cost significantly more than non-capital murder prosecutions seeking life imprisonment — largely due to the additional complexity of capital trial preparation, the mandatory penalty phase, and the extensive appellate review. A 2011 study in California estimated that a death penalty case costs approximately $184 million more per execution than a comparable case seeking life without parole. These costs have influenced the pragmatic arguments of some abolitionists.

The deterrence rationale for capital punishment — the claim that executions prevent would-be murderers from acting — is disputed by criminological research. Major studies, including a comprehensive 2012 National Research Council report, found insufficient evidence to conclude that the death penalty deters homicide. States that abolished the death penalty have not experienced consistent increases in murder rates.

The Eighth Amendment's prohibition on cruel and unusual punishment continues to generate litigation over execution methods, the length of time spent on death row, and the application of the death penalty to particular categories of offenders. Justice Stephen Breyer and others have argued that the death penalty as currently practiced — infrequently, arbitrarily, and after decades of delay — may itself constitute cruel and unusual punishment, though the Supreme Court has not accepted this argument as a whole.