Capital litigation is any court proceeding in which the possibility of imposing the death penalty is decided. In many jurisdictions, the death penalty is called capital punishment, and any criminal trial in which the death penalty can be imposed is called a capital trial. Generally, only persons who commit the most serious homicides are subject to capital punishment. Capital punishment is of course the most serious and irrevocable of punishments, so capital litigation has many special features. It concerns not only the accused person's guilt but also whether he or she is the sort of offender who was properly sentenced to death.
Some jurisdictions impose capital punishment for premeditated murder, or murder of a law enforcement officer, or for other serious homicides. In those jurisdictions, any trial for that type of murder will be capital litigation. The first phase of any such capital litigation is much like any other criminal trial, i.e., to determine the guilt or innocence of the defendant.
Should the accused person or defendant be found guilty in a capital trial, the the trial moves to the penalty phase. That phase focuses on whether the accused should be sentenced to death or a term in prison. In jurisdictions in the U.S. that have the death penalty, for example, this process often focuses on aggravating factors in favor of imposing capital punishment and mitigating factors which weigh against imposing that sentence. Proving or disproving these mitigating and aggravating factors is an important part of capital litigation.
Jurisdictions that use capital punishment usually provide for extensive automatic appeals. Some criminal defense attorneys specialize in handling death penalty appeals. The appeals are intended to weigh carefully whether the evidence supported the defendant's conviction. They also review among other things whether the accused was properly sentenced to suffer capital punishment based on the aggravating and mitigating factors or whether there were any procedural errors made during the trial.
In countries that have a written constitution, capital litigation may also focus on whether a death sentence is constitutionally permissible. The U.S. constitution for example, prohibits "cruel and unusual punishments." An issue often raised on appeal is whether the method of execution to be used to impose the penalty is constitutional. Some attorneys who specialize in capital litigation focus almost entirely on these constitutional challenges rather than on the individual facts and issues raised by a particular case. Capital litigation focusing on these constitutional issues has, for example, challenged whether lethal injection is too cruel to use as a form of execution.