Basic Concepts of Probability and Statistics in the Law

When as a practicing lawyer I published my ?rst article on statistical evidence in 1966, the editors of the Harvard Law Review told me that a mathematical equa- 1 tion had never before appeared in the review. This hardly seems possible - but if they meant a serious mathematical equation, perhaps they were right. Today all that has changed in legal academia. Whole journals are devoted to scienti?c methods in law or empirical studies of legal institutions. Much of this work involves statistics. Columbia Law School, where I teach, has a professor of law and epidemiology and other law schools have similar “law and” professorships. Many offer courses on statistics (I teach one) or, more broadly, on law and social science. The same is true of practice. Where there are data to parse in a litigation, stat- ticians and other experts using statistical tools now frequently testify. And judges must understand them. In 1993, in its landmark Daubert decision, the Supreme Court commanded federal judges to penetrate scienti?c evidence and ?nd it “re- 2 liable” before allowing it in evidence. It is emblematic of the rise of statistics in the law that the evidence at issue in that much-cited case included a series of epidemiological studies. The Supreme Court’s new requirement made the Federal Judicial Center’s Reference Manual on Scienti?c Evidence, which appeared at about the same time, a best seller. It has several important chapters on statistics.

This book sets out basic statistical tools as they have been applied in actual legal disputes. Examples range over diverse fields of law, such as identification evidence, mass torts, securities law, environmental regulation, and capital punishment, among many others. In some notable cases, such as the U.S. Supreme Court’s decision in Bush v. Gore, the book explores aspects of the statistical evidence that were unrecognized or misconceived by the parties or the court. For the statistics student, the book will give a deeper appreciation of foundation concepts and provide a wealth of real life applications. For the lawyer, or law student, the book will introduce a subject that has become increasingly important both in litigation and in studies of the legal system. The book is self-contained and may be read without background in probability or statistics.

Michael O. Finkelstein is a lawyer and has been described as a pioneer in the use of statistics in law. He has for many years taught Statistics for Lawyers at Columbia Law School, and has also taught this subject at Harvard, Yale, and the University of Pennsylvania law schools. In addition to numerous articles, he is the author of Quantitative Methods in Law, published in 1978, and is the co-author with Professor Bruce Levin of Statistics for Lawyers, first published in 1990 and now in its second edition.