This is far higher than the percentage of murder victims who are white. The juvenile death penalty is almost universally outlawed. Since 1990 the US is one of only six countries known to have executed persons who were under age 18 at the time of the crime. The others are Iran, Nigeria, Pakistan, Saudi Arabia and Yemen. Fortunately, Illinois does not allow the juvenile death penalty.
International law prohibits executing the mentally impaired.
But according to Amnesty International, more than 30 mentally impaired persons have been executed in the US since 1989. The UN Special Expert also noted other reasons for the arbitrariness of who gets the death penalty in the US, such as excessive prosecutorial discretion in deciding whether to ask for the death penalty. The UN Human Rights Commission has called on countries that still have the death penalty to stay executions, when ordered or requested to do so by international bodies of appropriate jurisdiction. In a third case, Texas refused a similar request from the Inter-American Commission on Human Rights. International law requires that foreign nationals who are arrested be advised without delay of their right to contact their consulates for assistance.