Roper v. Simmons, , was a landmark decision of the United States Supreme Court. The Court ruled that it is unconstitutional to execute a person for crimes they committed before they were 18 years old. This decision affected 25 states in the country, which still allowed executions of children under age 18. Also, the decision reversed the Court's past ruling in "Stanford v. Kentucky", , which had said that executions of children ages 1618 were sometimes legal. 