In a series of decisions between 1970 and 1979, the Supreme Court has addressed the constitutionality of juries of fewer than 12 persons and juries deliberating under less than unanimous rules of decision. These decisions have been the subject of substantial research and commentary by social scientists and statisticians. In Ballew v. Georgia, the Court established a minimum jury size of six in State criminal cases, and the lead opinion relied heavily on social science research and commentary. The article discusses the implications of the Ballew decision for social scientists interested in having their research used by the courts. Obstacles to judicial use of social science research are noted. These include the timing of judicial decisions, the adversary system, and judicial adherence to precedent. Although formidable, these obstacles are not insurmountable. In order to produce and present data in a form suitable for consideration in the judicial process, social scientists must (1) identify empirical issues in the legal process through legal publications and interest groups, (2) consult with legal experts in carrying out research and in criticizing and summarizing research results, and (3) present their research to the courts by publishing in legal journals, working with parties to appellate cases, filing true amicus curiae briefs, and participating as experts at the trial stages of the case. The challenge to social scientists and lawyers acting together is to provide courts with information about human behavior that is worthy of consideration in important legal decisions. Footnotes and references are given. (Author abstract modified)