How Capital Case Procedure and Jury Selection Work

A capital case works differently from any other criminal prosecution: eligibility is narrowed by the Constitution before charges are filed, the prosecution must give formal notice that it will seek death, jurors are screened for their views on the punishment, the trial itself splits into separate guilt and penalty phases, and a death sentence triggers layers of mandatory appellate and post-conviction review. Understanding how capital case procedure works means following that track from the first charging decision through federal habeas corpus, because the safeguards at each stage exist to satisfy the rule the Supreme Court set in Gregg v. Georgia: a death sentence is constitutional only when the process producing it is structured enough to prevent arbitrary results.¹

Who Is Actually Eligible for a Death Sentence

Not every defendant convicted of a capital-eligible crime can receive a death sentence. The Supreme Court has placed categorical limits on who can be executed under the Eighth Amendment, and these apply before any of the procedural machinery below ever runs.

Age is the first bright line. Roper v. Simmons holds that executing anyone who was under 18 at the time of the offense violates the Eighth and Fourteenth Amendments.² There is no exception.

Intellectual disability is the second. Atkins v. Virginia bars execution of individuals with intellectual disabilities, though states define the clinical criteria and the procedures for proving it.³ Clinical definitions typically require significantly below-average intellectual functioning, serious limitations in adaptive skills, and onset before age 18.

Mental competency at the time of execution is the third. Ford v. Wainwright prohibits executing a prisoner who is insane; the practical test asks whether the prisoner understands the punishment about to be carried out and why.⁴

Finally, the death penalty is limited by the type of offense. Kennedy v. Louisiana holds that the Eighth Amendment bars death for any crime against an individual that did not result in, and was not intended to result in, the victim’s death.⁵ Offenses against the state, such as treason and espionage, are the recognized exception.

How the Prosecution Formally Seeks Death

A capital case does not become a capital case automatically. The prosecution has to file a formal notice declaring its intent to seek death and listing the specific aggravating factors it plans to prove. In the federal system, 18 U.S.C. § 3593 requires the notice a reasonable time before trial, so the defense knows exactly which aggravating circumstances are in play.⁶ That timing matters because preparing a capital defense requires investigation on a different scale than an ordinary felony.

Federal Authorization Runs Through the Attorney General

A local U.S. Attorney cannot unilaterally decide to seek death in a federal case. Before seeking an indictment on a capital-eligible charge, the prosecutor must consult the Department of Justice’s Capital Case Section and submit a prosecution memorandum, a death penalty evaluation form, and the existing and proposed indictments. A Capital Review Committee considers the materials and makes a recommendation. The Attorney General personally makes the final decision, and the local office cannot file or amend a death notice without Capital Case Section approval.⁷

State Notice Procedures

State procedures vary but share the basic structure. The prosecution files a notice with the court and serves it on the defense early in the pretrial phase, identifying the statutory aggravating factors it intends to prove. Once that notice is filed, the case moves onto a specialized track with longer timelines, additional hearings, and increased defense funding.

Jury Selection and Death Qualification

Picking a jury in a capital case can take weeks. The process, called death qualification, requires attorneys to question each prospective juror about whether they can genuinely consider both possible sentences: life imprisonment and death. A juror who could only vote one way, regardless of the evidence, is not qualified to sit.

Two Supreme Court decisions mark the limits. Witherspoon v. Illinois, as refined by Wainwright v. Witt, asks whether a juror’s views on the death penalty would “prevent or substantially impair” the performance of their duties.⁸ A juror who personally opposes the death penalty but can follow the law stays; one who could never vote for it is excused for cause. Morgan v. Illinois protects the defendant on the other side: a juror who would automatically impose death on any murder conviction is equally disqualified.⁹

Both sides also receive expanded peremptory challenges. In federal court, each side gets 20 peremptory challenges in a capital case, compared to 6 for the government and 10 for the defense in a standard felony.¹⁰ State rules differ but almost all elevate the numbers for capital cases. Peremptory strikes remain subject to Batson v. Kentucky, which prohibits striking jurors on the basis of race and shifts the burden to the striking party to offer a race-neutral explanation when a pattern is shown.¹¹

The Trial Splits Into Two Phases

Capital trials are bifurcated. Gregg v. Georgia required this structure to keep emotionally charged sentencing evidence from contaminating the jury’s assessment of guilt.¹ The guilt phase operates like any serious felony trial: the prosecution must prove every element of the charged offense beyond a reasonable doubt, and the defendant retains all standard trial rights. An acquittal ends the case. A conviction moves the same jury into the penalty phase, where the question is no longer what the defendant did but what sentence should follow.

Aggravating and Mitigating Evidence

The penalty phase decides between death and life imprisonment without the possibility of release. The decision is a structured weighing of aggravating factors against mitigating ones.

Aggravating Factors

Aggravating factors are the prosecution’s case for death. These are specific statutory circumstances that make the crime especially serious. In the federal system, 18 U.S.C. § 3592 lists factors such as prior convictions for violent felonies, committing the offense during another serious crime, or targeting a particularly vulnerable victim.¹² Each aggravating factor must be proved beyond a reasonable doubt.⁶ Under Ring v. Arizona, those findings have to come from a jury, not a judge, because aggravating factors function as the equivalent of an element of a greater offense and trigger the Sixth Amendment right to a jury trial.¹³

Mitigating Factors

Mitigating factors are the defense’s case for life. Lockett v. Ohio set an extraordinarily broad standard: the sentencer cannot be prevented from considering any aspect of the defendant’s character, record, or circumstances offered as a reason for a sentence less than death.¹⁴ Childhood abuse, mental illness, brain damage, military service, remorse, a minor role in the offense—all qualify. The burden is lighter than for aggravators. In the federal system, mitigating factors must be established by a preponderance of the information,⁶ and the Supreme Court has held that placing this burden on the defendant does not violate the Constitution.¹⁵

Weighing and Unanimity

The jury then weighs whether the aggravating factors sufficiently outweigh the mitigating ones to justify death. In federal cases, every aggravating factor must be found unanimously, but a single juror who finds a mitigating factor can treat it as established regardless of the other jurors. The final death recommendation must itself be unanimous. If the jury cannot unanimously agree on death, the court imposes life imprisonment without the possibility of release or another lesser sentence.⁶ Most states also require unanimity for death, though a small number allow non-unanimous recommendations or let a judge impose death when the jury deadlocks.

The Defense Team Required by Law

Federal law requires the court to appoint two attorneys for any defendant charged with a capital crime, and at least one of them must have specific experience in capital cases.¹⁶ The court considers the recommendation of the Federal Public Defender organization for the district when making the appointment.

The team also includes a mitigation specialist whose job is to build the case for life. That work involves gathering medical, educational, military, and social service records, interviewing family members across generations, and identifying issues that need evaluation by mental health professionals. Trauma, abuse, cognitive disabilities, and undiagnosed mental illness often surface during this investigation, and the findings shape strategy at trial as well as penalty-phase evidence. Underfunding or understaffing the mitigation investigation is one of the most common grounds raised later in ineffective assistance of counsel claims.

Appellate Review After a Death Sentence

A death sentence triggers a direct appeal that is automatic in most jurisdictions. The appeal goes to the state’s highest court or, in federal cases, to the appropriate circuit court. Reviewing courts examine the full record for legal errors, constitutional violations, and the fairness of the sentence on the individual facts of the case. Special appellate review of both the conviction and the sentence was one of the procedural safeguards Gregg identified as making the modern death penalty constitutional.¹

Some states also conduct comparative proportionality review, checking whether the sentence is consistent with penalties in similar cases. The practice is common but not constitutionally required; Pulley v. Harris held that the Eighth Amendment does not demand proportionality review as an invariable rule in every capital case.¹⁷

State Post-Conviction Review

Once the direct appeal is resolved, a capital defendant can pursue state post-conviction relief, sometimes called collateral review. This stage is where claims that depend on evidence outside the trial record get raised. Ineffective assistance of counsel is the most frequent claim here, often based on the defense team’s failure to investigate or present mitigating evidence. New evidence of innocence, prosecutorial misconduct, and juror bias can also form the basis of post-conviction claims.

Federal Habeas Corpus

After state remedies are exhausted, a capital defendant may petition a federal court for a writ of habeas corpus under 28 U.S.C. § 2254. Federal courts will not hear the petition unless all available state court remedies have been pursued.¹⁸ The Antiterrorism and Effective Death Penalty Act of 1996 sets a one-year filing deadline that generally runs from the date the state judgment becomes final after direct review.¹⁹ A properly filed state post-conviction petition pauses that clock, but missing the deadline can permanently foreclose federal review.

Federal habeas review is narrow by design. The federal court does not retry the case or second-guess reasonable state court decisions. It asks whether the state court’s ruling was contrary to, or an unreasonable application of, clearly established Supreme Court precedent. Even so, habeas proceedings in capital cases often last years and sometimes result in vacated sentences or new penalty-phase trials.

Where Federal Policy Currently Stands

The federal death penalty’s operational status has shifted repeatedly. The Biden administration’s Attorney General rescinded the federal execution protocol in January 2025. The current administration reversed course, rescinding that moratorium, reinstating the protocol that uses pentobarbital as the lethal agent, and directing the Bureau of Prisons to expand available methods of execution. The Department of Justice has also signaled plans to streamline the authorization process for seeking death sentences and to restrict the timing of clemency petitions.²⁰ These policy changes do not alter the constitutional procedural requirements above. They do affect how aggressively the federal government pursues capital charges and how quickly executions move forward once appellate review is complete.

1
Constitution Annotated. Gregg v. Georgia and Limits on Death Penalty
2
Justia Law. Roper v. Simmons, 543 U.S. 551 (2005)
3
Justia Law. Atkins v. Virginia, 536 U.S. 304 (2002)
4
Legal Information Institute. Ford v. Wainwright, 477 U.S. 399 (1986)
5
Justia Law. Kennedy v. Louisiana, 554 U.S. 407 (2008)
6
Office of the Law Revision Counsel. 18 USC 3593 – Special Hearing to Determine Whether a Sentence of Death Is Justified
7
United States Department of Justice. Justice Manual 9-10.000 – Capital Crimes
8
Legal Information Institute. Death Penalty and Requirement of Impartial Jury
9
Legal Information Institute. Morgan v. Illinois, 504 U.S. 719 (1992)
10
Legal Information Institute. Federal Rules of Criminal Procedure Rule 24
11
Justia Law. Batson v. Kentucky, 476 U.S. 79 (1986)
12
Office of the Law Revision Counsel. 18 USC 3592 – Mitigating and Aggravating Factors to Be Considered in Determining Whether a Sentence of Death Is Justified
13
Justia Law. Ring v. Arizona, 536 U.S. 584 (2002)
14
Justia Law. Lockett v. Ohio, 438 U.S. 586 (1978)
15
Constitution Annotated. Eighth Amendment – Cruel and Unusual Punishment – Role of Jury and Consideration of Evidence
16
Office of the Law Revision Counsel. 18 USC 3005 – Counsel and Witnesses in Capital Cases
17
Justia Law. Pulley v. Harris, 465 U.S. 37 (1984)
18
Office of the Law Revision Counsel. 28 USC 2254 – State Custody; Remedies in Federal Courts
19
Office of the Law Revision Counsel. 28 USC 2244 – Finality of Determination
20
United States Department of Justice. The Justice Department Takes Actions to Strengthen the Federal Death Penalty