In its 5–4 decision in Tison v. Arizona (1987), the Supreme Court put forth disputable empirical assertions about where community sentiment stood on the death penalty for felony-murder accessories. The Tison majority claimed that the community would support the death sentence for an accessory where (1) major participation and (2) reckless indifference to human life were shown. Two experiments were run to test these empirical assertions, and the results indicate quite the opposite. By a wide majority, community sentiment rejects the death penalty for such an accessory and rejects equal treatment of principal and accessory. Even beyond the death penalty question, to the issue of conviction under the felony-murder rule per se, attributions of causal and moral responsibility showed the principle of proportionality reigning supreme. Implications for how the Supreme Court goes about doing social science are discussed.