Marshall Hypotheses

The Marshall hypotheses are a series of conjectures by Supreme Court Justice Thurgood Marshall regarding the value of opinion poll data on public sentiments about capital punishment. Because the results of such polls can be of great importance to the U.S. Supreme Court's assessment of the constitutionality of various criminal statutes and policies and practices, the validity of these data is especially important. Justice Marshall's opinions regarding both the importance of public opinion data and the limits of their validity opened an area of social scientific research. This entry describes the origins and precise nature of the Marshall hypotheses. This is followed by a brief review of the social scientific studies (both the methodologies employed and the findings of these studies) that were spawned from Justice Marshall's claims.

[Page 482]In 1972, the U.S. Supreme Court ruled in the case of Furman v. Georgia that all death penalty statutes within the United States violated the Constitution's Eighth Amendment ban on cruel and unusual punishment because they required jurors in capital cases to make sentencing recommendations without any legal guidance as to what characteristics of the offense, the offender, and/or the victim should be employed to distinguish between those to be sentenced to death and those to be punished by a sentence less than death. This unguided discretion also led some capital juries to base their capital sentencing decisions on legally irrelevant factors such as the victim's or the offender's race or socioeconomic status. The pattern of sentencing that resulted from this unguided discretion was found by the Court to be both arbitrary, capricious, and discriminatory and, thus, in violation of “the evolving standards of decency that mark the progress of a maturing society”—one of the legal tests used by the Supreme Court to assess cruel and unusual punishment.

One of the great problems for the Court when invoking the evolving standards of decency test is to identify valid and reliable indicators of these evolving standards. Frequently the Court has examined the results of public opinion polls and social scientific research on opinions and attitudes. The Court, however, has not been particularly impressed with the accuracy of such polls. In fact, one of the first to criticize the validity of the results of public opinion polls on the level of support for capital punishment was former Supreme Court Justice Thurgood Marshall, the first Black to be appointed to the U.S. Supreme Court. Ironically, Marshall not only presented a critique of these polls but also emphasized their importance.

Justice Marshall noted that capital punishment would be constitutionally invalid if the public abhorred it; furthermore, he argued that it was imperative for the Court to discern the sentiment of an informed public. He emphasized that the probative value of public opinion regarding capital punishment lay only in the opinions of those who were knowledgeable or informed. Marshall opined that support for the death penalty was largely the product of a lack of information about it, but, if the public were fully informed, the majority would conclude that capital punishment is immoral and unconstitutional. Marshall acknowledged one exception to this assertion: for those who support capital punishment for retributive reasons (i.e., eye for an eye, just desert, etc.), knowledge about the death penalty would not be persuasive.

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