Science in the Courtroom
Breyer, Stephen G., Issues in Science and Technology
Judges have begun to work more closely with scientists to ensure that their rulings are founded on scientifically sound knowledge.
In this age of science, science should expect to find a warm welcome, perhaps a permanent home, in our courtrooms. The legal disputes before us increasingly involve the principles and tools of science. Proper resolution of those disputes matters not just to the litigants, but also to the general public-those who live in our technologically complex society and whom the law must serve. Our decisions should reflect a proper scientific and technical understanding so that the law can respond to the needs of the public.
Consider, for example, how often our cases today involve statistics, a tool familiar to social scientists and economists but, until our own generation, not to many judges. Only last year, the U.S. Supreme Court heard two cases that involved consideration of statistical evidence. In Hunt v. Cromartie, we ruled that summary judgment was not appropriate in an action brought against various state officials that challenged a congressional redistricting plan as racially motivated in violation of the Equal Protection Clause. In determining that disputed material facts existed regarding the motive of the state legislature in redrawing the redistricting plan, we placed great weight on a statistical analysis that offered a plausible alternative interpretation that did not involve an improper racial motive. Assessing the plausibility of this alternative explanation required knowledge of the strength of the statistical correlation between race and partisanship, understanding of the consequences of restricting the analysis to a subset of precincts, and understanding of the relationships among alternative measures of partisan support.
In Department of Commerce v. United States House of Representatives, residents of a number of states challenged the constitutionality of a plan to use two forms of statistical sampling in the upcoming decennial census to adjust for expected "undercounting" of certain identifiable groups. Before examining the constitutional issue, we had to determine whether the residents challenging the plan had standing to sue because of injuries they would be likely to suffer as a result of the sampling 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 whether the statistical estimation techniques were consistent with a federal statute.
In each of these two 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 routinely asked 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. In 1997, we were asked to decide whether the Constitution contains a "right to die." The specific legal question was whether the federal Constitution, which prohibits government from depriving "any person" of "liberty" without "due process of law" requires a state to permit a doctor's assistance in the suicide of a terminally ill patient. Is the "right to assisted suicide" part of the liberty that the Constitution protects? Underlying the legal question was a medical question: To what extent can medical technology reduce or eliminate the risk of dying in severe pain? The medical question did not determine the answer to the legal question, but to do our legal job properly, we needed to develop an informed, although necessarily approximate, understanding of the state of that relevant scientific art. …