plan. In making this assessment, it was necessary to apply the two sampling strategies to population data in order to predict the changes in congressional apportionment that would most likely occur under each proposed strategy. After resolving the standing issue, we had to determine if the statistical estimation techniques were consistent with a federal statute.

In each of these cases, we judges were not asked to become expert statisticians, but we were expected to understand how the statistical analyses worked. Trial judges today are asked routinely to understand statistics at least as well, and probably better.

But science is far more than tools, such as statistics. And that “more” increasingly enters directly into the courtroom. The Supreme Court, for example, has recently decided cases involving basic questions of human liberty, the resolution of which demanded an understanding of scientific matters. Recently we were asked to decide whether a state’s method of administering a lethal injection to condemned inmates constituted cruel and unusual punishment in violation of the Eighth Amendment.4 And in 1997, we were asked to decide whether the Constitution protects a right to physician-assisted suicide.5 Underlying the legal questions in these cases were medical questions: What effect does a certain combination of drugs, administered in certain doses, have on the human body, and to what extent can medical technology reduce or eliminate the risk of dying in severe pain? The medical questions did not determine the answer to the legal questions, but to do our legal job properly, we needed to develop an informed—although necessarily approximate—understanding of the science.

Nor were the lethal-injection and “right-to-die” cases unique in this respect. A different case concerned a criminal defendant who was found to be mentally competent to stand trial but not mentally competent to represent himself. We held that a state may insist that such a defendant proceed to trial with counsel.6 Our opinion was grounded in scientific literature suggesting that mental illness can impair functioning in different ways, and consequently that a defendant may be competent to stand trial yet unable to carry out the tasks needed to present his own defense.

The Supreme Court’s docket is only illustrative. Scientific issues permeate the law. Criminal courts consider the scientific validity of, say, DNA sampling or voiceprints, or expert predictions of defendants’ “future dangerousness,” which can lead courts or juries to authorize or withhold the punishment of death. Courts review the reasonableness of administrative agency conclusions about the safety of a drug, the risks attending nuclear waste disposal, the leakage potential of a toxic waste dump, or the risks to wildlife associated with the building of a dam. Patent law cases can turn almost entirely on an understanding of the underlying technical

4. Baze v. Rees, 128 S. Ct. 1520 (2008).

5. Washington v. Glucksberg, 521 U.S. 702 (1997); Vacco v. Quill, 521 U.S. 793 (1997).

6. Indiana v. Edwards, 128 S. Ct. 2379 (2008).



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