Juvenile offenders.

The death penalty for juvenile offenders (criminals aged under 18 years at the time of their crime although the legal or accepted definition of juvenile offender may vary from one jurisdiction to another) has become increasingly rare. Considering the age of majority is not 18 in some countries or has not been clearly defined in law, since 1990 ten countries have executed offenders who were considered juveniles at the time of their crimes: The People's Republic of China (PRC), Bangladesh, Democratic Republic of Congo, Iran, Iraq, Japan, Nigeria, Pakistan, Saudi Arabia, Sudan, the United States, and Yemen. China, Pakistan, the United States, Yemen and Saudi Arabia have since raised the minimum age to 18. Amnesty International has recorded 61 verified executions since then, in several countries, of both juveniles and adults who had been convicted of committing their offenses as juveniles. The PRC does not allow for the execution of those under 18, but child executions have reportedly taken place.

The United Nations Convention on the Rights of the Child, which forbids capital punishment for juveniles under article 37(a), has been signed by all countries and subsequently ratified by all signatories with the exception of the United States (despite the US Supreme Court decisions abolishing the practice). The UN Sub-Commission on the Promotion and Protection of Human Rights maintains that the death penalty for juveniles has become contrary to a jus cogens of customary international law. A majority of countries are also party to the U.N. International Covenant on Civil and Political Rights (whose Article 6.5 also states that "Sentence of death shall not be imposed for crimes committed by persons below eighteen years of age...").

Methods.

The following methods of execution have been used by various U.S. states:

Lethal injection, 

Electrocution and gas inhalation (some U.S. states, but only if the prisoner requests it or if lethal injection is unavailable), and

Inert gas asphyxiation (Some U.S. states, Oklahoma, Mississippi, Alabama)