On August 18, 1986, seventy-two Nobel laureates, seventeen state academies of science, and seven other scientific organizations submitted an amicus curiae brief to the Supreme Court of the United States in which they defined and agreed upon the nature and scope of science. The brief was submitted in response to the Louisiana Balanced TreatmentAct for creation science and evolution science that had been struck down in the Federal Court of Louisiana in 1985 and was being appealed to the Supreme Court. (...) The Louisiana trial in general and the amicus curiae brief in particular have historical significance for the history of science, being unique in the collective mobilization of scientists both in defense of and in defining science. This article describes the origin and significance of the brief. (shrink)