A capital crime is an offense for which the law allows the death penalty as a possible punishment. In the United States, that category is narrow: almost every capital crime is a murder committed under circumstances the legislature has singled out as especially serious, together with a small group of federal offenses against the nation itself, such as treason and espionage. Twenty-seven states, the federal government, and the US military currently authorize capital punishment, though several of those states have paused executions through governor-ordered moratoria.
Federal Capital Offenses
Federal law splits capital crimes into two groups. The first is offenses against the United States that do not require anyone to have died. Treason, defined as levying war against the United States or giving aid and comfort to its enemies, is punishable by death or by imprisonment of at least five years.1Office of the Law Revision Counsel. 18 USC 2381 – Treason Espionage involving the transmission of national defense information to a foreign power can also carry a death sentence, but only when the offense resulted in the death of an identified US agent or directly concerned nuclear weapons, military satellites, early warning systems, war plans, or other major defense systems.2Office of the Law Revision Counsel. 18 USC 794 – Gathering or Delivering Defense Information to Aid Foreign Government
The second group is federal murder statutes. For any of these to carry death, prosecutors must prove the defendant intentionally killed someone, intentionally caused serious bodily injury that led to death, participated in violence expecting lethal force would be used, or engaged in conduct showing reckless disregard for human life that resulted in death.3Office of the Law Revision Counsel. 18 USC 3591 – Sentence of Death Dozens of specific statutes fall under this umbrella. Common examples include the murder of a federal judge or law enforcement officer, killings during an aircraft hijacking or a kidnapping, murders connected to terrorism or weapons of mass destruction, and large-scale drug trafficking operations where someone died.
A federal moratorium imposed in 2021 was lifted in February 2025. Under a directive issued that month, federal prosecutors are expected to seek the death penalty for the murder of law enforcement officers and for capital crimes committed by individuals unlawfully present in the United States, absent significant mitigating circumstances. The directive also reinstated a 2018 policy encouraging capital charges in drug-related prosecutions and expanded it to cover crimes linked to cartels and transnational criminal organizations.
State Capital Offenses
Most death sentences in the United States come from state courts, not federal ones. Among the 27 states that authorize capital punishment, the qualifying offense is almost universally first-degree murder accompanied by at least one specific aggravating circumstance. A handful of states also technically list treason as a capital offense, but in practice state capital prosecutions are murder cases. The prosecutor has to prove both the killing itself and a statutory aggravating factor that elevates the crime beyond ordinary homicide.
The practical picture varies widely from state to state. Some jurisdictions keep the death penalty on the books but rarely use it. California, Oregon, Ohio, and Pennsylvania each have governor-imposed moratoria that halt executions even though courts can still hand down death sentences. Delaware formally removed the death penalty from state law in 2024, bringing the total number of abolitionist states and the District of Columbia to 24 jurisdictions without capital punishment.
Aggravating Factors That Make a Murder Capital
An aggravating factor is a specific circumstance, defined by statute, that makes a murder eligible for the death penalty. Without at least one aggravator, a first-degree murder conviction cannot result in a death sentence regardless of how brutal the crime was. The jury must find the aggravating factor proven beyond a reasonable doubt before a defendant becomes death-eligible, and the Supreme Court has held that this finding must come from the jury rather than a judge.4Cornell Law School. Ring v Arizona
The specific list differs from state to state, but certain aggravators show up across nearly every death penalty jurisdiction:
- Killing a law enforcement officer, firefighter, corrections officer, or other first responder acting in the line of duty, or killing a child or a particularly vulnerable person such as an elderly or disabled individual.
- A killing committed during another violent felony like robbery, kidnapping, sexual assault, or arson. This is often called “felony murder” and is one of the most frequently charged aggravators.
- Murder committed for financial gain, including contract killings and murder-for-hire schemes.
- The killing of more than one person in the same criminal episode or as part of a pattern.
- Murders involving torture, exceptional cruelty, or methods that endangered many people beyond the intended victim.
The number of listed aggravators ranges from around 10 in some states to more than 20 in others. Alabama, for example, defines 14 statutory aggravating factors for intentional murder.5Death Penalty Information Center. Summary of State Death Penalty Statutes
Finding an aggravator makes a defendant eligible for death; it does not require it. After the guilt verdict, a capital case moves to a separate sentencing phase where the defense can present mitigating evidence about the defendant’s background, character, mental state, and role in the offense. The Supreme Court has held that the Constitution requires sentencers to consider virtually any mitigating evidence a defendant offers, and a state law restricting what mitigating evidence the jury can hear is unconstitutional.6Oyez. Lockett v Ohio In federal cases, the sentencing jury must consist of 12 members and its decision for death must be unanimous.7Office of the Law Revision Counsel. 18 USC 3593 – Special Hearing To Determine Whether a Sentence of Death Is Justified
Constitutional Limits on Who Can Be Executed
Even when a crime technically qualifies as capital, the Eighth Amendment’s ban on cruel and unusual punishment puts hard limits on who can be put to death. The Supreme Court has drawn four significant lines.
Non-Homicide Crimes Against Individuals
The most important boundary: with the narrow exception of crimes against the state like treason and espionage, the death penalty is reserved for crimes that take a victim’s life. In Kennedy v. Louisiana (2008), the Court struck down a state law authorizing death for the rape of a child, holding that non-homicide crimes against individuals, no matter how devastating, do not warrant capital punishment. The Court concluded that such offenses “cannot compare to murder in their severity and irrevocability.”8Cornell Law School. Kennedy v Louisiana
Offenders Under 18
In Roper v. Simmons (2005), the Court ruled that the Eighth Amendment forbids the death penalty for anyone who was under 18 at the time of the crime, citing juveniles’ developmental immaturity, vulnerability to outside pressure, and still-forming character.9Justia U.S. Supreme Court Center. Roper v Simmons, 543 US 551 (2005) The under-18 bar is also written directly into the federal death penalty statute.3Office of the Law Revision Counsel. 18 USC 3591 – Sentence of Death
Defendants With Intellectual Disabilities
In Atkins v. Virginia (2002), the Court held that executing individuals with intellectual disabilities violates the Eighth Amendment. The reasoning rested on diminished moral culpability and a heightened risk of wrongful conviction, since intellectually disabled defendants are more likely to give false confessions, struggle to assist their attorneys, and present poorly as witnesses.10Justia U.S. Supreme Court Center. Atkins v Virginia, 536 US 304 (2002) Atkins left states to design the procedures for determining intellectual disability, but the Court later limited how rigid those procedures can be. In Hall v. Florida (2014), it struck down a Florida rule that required defendants to prove an IQ of 70 or below before presenting any additional evidence, holding that IQ scores carry an inherent margin of error and that a defendant whose score falls within that range must be allowed to present other evidence of intellectual disability, including deficits in everyday adaptive functioning.11Justia U.S. Supreme Court Center. Hall v Florida, 572 US 701 (2014)
Prisoners Who Have Become Incompetent
A separate rule, established in Ford v. Wainwright (1986), prohibits executing a prisoner who is currently insane, even if they were competent at the time of the crime and trial. The standard asks whether the prisoner is aware of the impending execution and understands the reason for it. A prisoner who has lost that awareness through mental illness cannot be put to death.12Cornell Law School. Ford v Wainwright, 477 US 399 (1986)
Where Capital Punishment Applies Today
Twenty-seven states, the federal government, and the US military authorize the death penalty. Of those states, four — California, Oregon, Ohio, and Pennsylvania — have governor-ordered moratoria pausing executions. Twenty-three states and the District of Columbia have no death penalty at all, with Delaware the most recent to repeal in 2024. Whether a specific killing is a capital crime therefore depends on three things stacked together: where it happened, whether it meets the statutory definition of first-degree murder (or one of the federal non-homicide offenses), and whether the facts match a listed aggravating factor. Absent all three, the death penalty is off the table even in jurisdictions that keep it on the books.