David Keen v. State of Tennessee - Dissent

In Van Tran v. State, 66 S.W.3d 790, 792 (Tenn. 2001), this Court held that “the Eighth Amendment to the United States Constitution and article I, § 16 of the Tennessee Constitution prohibit the execution of [intellectually disabled] individuals because such executions violate evolving standards of decency that mark the progress of a maturing society, are grossly disproportionate, and serve no valid penological purpose in any case.” The next year, the United States Supreme Court reached the same conclusion:
We are not persuaded that the execution of [intellectually disabled] criminals will measurably advance the deterrent or the retributive purpose of the death penalty. Construing and applying the Eighth Amendment in the light of our “evolving standards of decency,” we therefore conclude that such punishment is excessive and that the Constitution “places a substantive restriction on the State’s power to take the life” of a[n intellectually disabled] offender.