The legal administration of the death penalty in the United States is complex. Typically, it involves four critical steps: (1) Sentencing, (2) Direct Review, (3) State Collateral Review, and (4) Federal Habeas Corpus. Recently, a narrow and final fifth level of process—(5) the Section 1983 Challenge—has become increasingly important. (Clemency or Pardon, through which the Governor or President of the jurisdiction can unilaterally reduce or abrogate a death sentence, is an executive rather than legal process.)

Direct review

If a defendant is sentenced to death at the trial level, the case then goes into a direct review. The direct review process is a typical legal appeal. An appellate court examines the record of evidence presented in the trial court and the law that the lower court applied and decides whether the decision was legally sound or not. Direct review of a capital sentencing hearing will result in one of three outcomes. If the appellate court finds that no significant legal errors occurred in the capital sentencing hearing, the appellate court will affirm the judgment, or let the sentence stand. If the appellate court finds that significant legal errors did occur, then it will reverse the judgment, or nullify the sentence and order a new capital sentencing hearing. Lastly, if the appellate court finds that no reasonable juror could find the defendant eligible for the death penalty, a rarity, then it will order the defendant acquitted, or legally innocent, of the death penalty and order him sentenced to the next most severe punishment for which the offense is eligible. A majority of death sentences, however — about 60% — survive the process of direct review intact.

State collateral review

At times when a death sentence is affirmed on direct review, it is considered final. Yet, supplemental methods to attack the judgment, though less familiar than a typical appeal, do remain. These supplemental remedies are considered collateral review, that is, an avenue for upsetting judgments that have become otherwise final. Where the prisoner received his death sentence in a state-level trial, as is usually the case, the first step in collateral review is State Collateral Review. (If the case is a federal death penalty case, it proceeds immediately from direct review to federal habeas corpus.) Although all states have some type of collateral review, the process varies widely from state to state. Generally, the purpose of these collateral proceedings is to permit the prisoner to challenge his sentence on grounds that could not have been raised reasonably at trial or on direct review. Most often these are claims, such as ineffective assistance of counsel, which require the court to consider new evidence outside the original trial record, something courts may not do in an ordinary appeal. State Collateral Review, though an important step in that it helps define the scope of subsequent review through Federal Habeas Corpus, is rarely successful in and of itself. Only around 6% of death sentences are overturned on State Collateral Review.

Federal habeas corpus

After a death sentence is affirmed in State Collateral Review, the prisoner may file for Federal Habeas Corpus, which is a unique type of lawsuit that can be brought in federal courts. Federal habeas corpus is a species of collateral review, and it is the only way that state prisoners may attack a death sentence in federal court (other than petitions for certiorari to the United States Supreme Court after both direct review and state collateral review). The scope of federal habeas corpus is governed by the Antiterrorism and Effective Death Penalty Act of 1996, which restricted significantly its previous scope. The purpose of Federal habeas corpus is to ensure that state courts, through the process of direct review and State Collateral Review, have done at least a reasonable job in protecting the prisoner's Federal Constitutional Rights. Prisoners may also use Federal habeas corpus suits to bring forth new evidence that they are innocent of the crime, though to be a valid defense at this late stage in the process, evidence of innocence must be truly compelling.

Review through federal habeas corpus is narrow in theory, but it is important in practice. According to Eric Freedman, 21% of death penalty cases are reversed through federal habeas corpus.

James Lieberman, a professor of law at the Columbia law school, stated in 1996 that his study found that when habeas corpus petitions in death penalty cases were traced from conviction to completition of the case that there was "a 40 percent success rate in all capital cases from 1978 to 1995." Similarly, a study by Ronald Tabek in a law review article puts the success rate in habeas corpus cases involving death row inmates even higher, finding that between "1976 and 1991, approximately 47% of the habeas petitions filed by death row inmates were granted." The different numbers are largely definitional, rather than substantive. Freedam's statistics looks at the percentage of all death penalty cases reversed, while the others look only at cases not reversed prior to habeas corpus review.

Section 1983 contested

Under the Antiterrorism and Effective Death Penalty Act, a state prisoner is ordinarily only allowed one suit for habeas corpus in federal court. If the federal courts refuse to issue a writ of habeas corpus, the Governor may set an execution date. In recent times, however, prisoners have postponed execution through a final round of federal litigation using the Civil Rights Act of 1871 — codified at 42 U.S.C. § 1983 — which allows people to bring lawsuits to protect their civil rights.

Traditionally, Section 1983 was of limited use for a state prisoner under sentence of death because the Supreme Court has held that habeas corpus, not Section 1983, is the only vehicle by which a state prisoner can challenge his judgment of death. In the recent Hill v. McDonough case, however, the United States Supreme Court approved the use of Section 1983 as a vehicle for challenging a state's method of execution as cruel and unusual punishment in violation of the Eighth Amendment. The theory is that a prisoner bringing such a challenge is not attacking directly his judgment of death, but rather the means that the judgment will be carried out. Therefore, the Supreme Court held in the Hill case, a prisoner can use Section 1983 rather than habeas corpus to bring the lawsuit. Yet, as Clarence Hill's own case shows, lower federal courts have often refused to hear suits challenging methods of execution on the ground that the prisoner brought the claim too late and only for the purposes of delay.

Mitigating factor

The United States Supreme Court in Penry v. Lynaugh and the United States Court of Appeals for the Fifth Circuit in Bigby v. Dretke have been clear in their decisions that jury instructions in death penalty cases that do not ask about mitigating factors regarding the defendant's mental health violate the defendant's Eighth Amendment rights, saying that the jury is to be instructed to consider mitigating factors when answering unrelated questions. This ruling suggests specific explanations to jury is necessary to weigh mitigating factors.