Capital punishment in the United States is limited under the Eighth Amendment to the United States Constitution to cases of homicide, crimes against the state, and crimes against humanity committed by mentally-competent adults.[1] In practice, it is only ever used in cases where aggravating circumstances exist, including aggravated murder, felony murder, and contract killing.
Capital punishment was a penalty at common law, for many felonies, and was enforced in all the American colonies prior to the Declaration of Independence. The death penalty is currently a legal sentence in 37 states and in the federal civilian and military legal systems. The methods of execution and the crimes subject to the penalty vary by jurisdiction and have varied widely