Under the Uniform Code of Military Justice, the death sentence may be imposed for premeditated and felony murder in aggravated circumstances. In many states, the law requires that the jury consider the question of the appropriate penalty in a separate phase of the trial following a guilty verdict. Because of its severity, the imposition of capital punishment is subject to unique protections and limitations and can be challenged by the defendant at various points in the proceedings. U.S. law places special emphasis on due process protection for those accused of capital offenses. The death penalty cannot be carried out unless imposed by a judgment of a competent court and unless the sentence is subject to appellate review.
Appellate review is always available.
Those states which do not mandate automatic review of capital sentences nonetheless authorize such review when the defendant wishes to appeal. The fact that a state appellate court reviews each death sentence to determine whether it is proportionate to other sentences imposed for similar crimes safeguards against the possibility that the sanctions will be imposed capriciously or arbitrarily. Typically, review is undertaken automatically as a matter of law, regardless of the defendant's wishes and is conducted by the state's highest appellate court. In states not providing automatic review, the defendant can appeal the sentence, the conviction or both. In 1996, Congress passed the Antiterrorism and Effective Death Penalty Act, which introduced a series of modifications to federal criminal procedures, including a number of changes to the federal law governing habeas corpus petitions.