My guess is that their decision was based on an interpertation of the 8th amendment, which reads
Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted.
Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted.
This I know, but since when is executing a 17yo murderer "cruel and unusual"?
The answer is "When 5 Supreme Court justices flaut the will of the voting public with fabricated new rights never before seen in the Constitution."