In Roper v. Simmons, 543 U.S. 551 (2005), the U.S. Supreme Court declared that that Eighth Amendment of the U.S. Constitution prohibited executing anyone for a murder they committed before the age of 18. The heinous crime at issue in the case consisted of defendant breaking into a helpless woman's home as she slept and then forcing her into her car to drive it to a river.
"Using duct tape to cover her eyes and mouth and bind her hands, the two [teenage] perpetrators put Mrs. Crook in her minivan and drove to a state park. They reinforced the bindings, covered her head with a towel, and walked her to a railroad trestle spanning the Meramec River. There they tied her hands and feet together with electrical wire, wrapped her whole face in duct tape and threw her from the bridge, drowning her in the waters below."
Despite being sentenced to death for this crime by a jury in Missouri, and despite the sentence being upheld by the Missouri Supreme Court, the U.S. Supreme Court overturned this punishment as unconstitutional because the defendant was only 17 years old rather than over 18.
- 543 U.S. at 556-57.