A significant ruling is that in the case of Roper v. Simmons in 2005, in which SCOTUS ruled that the death penalty cannot be applied to juveniles. In essence, the Court found that juveniles cannot be held to the same standards as adults in capital cases, as they lack maturity, and are more easily swayed by others.
The Court has found that the death penalty is not a direct contradiction of the Eighth Amendment, so long as the principle of due process (as outlined in the Fourteenth Amendment) is followed. However, the Court has also ruled that the punishment must be in proportion to the crime. Methods of execution are determined by the legislature of a state, but the method of execution cannot be inordinately harsh. Electrocution and hanging have not been outlawed in all states, and SCOTUS struck down a challenge to lethal execution in the 2008 case of Baze v. Rees, ruling that lethal injection did not constitute a violation of the Eighth Amendment.