Jury size, majorities required for acquittal or conviction and correctness of juror decisions in criminal trials are studied. The article draws heavily on ideas presented in a previous article [1] which updated a model suggested by Poisson. Briefly, a model is developed and then examined, employing data from Kalven and Zeisel [2] on the American legal system. Comparisons of the American experience with French data from the early 19th century are made through the use of the model. Recent U. S. Supreme Court decisions in criminal trials regarding jury size and the relaxation of unanimity for decisions in criminal trials make these studies pertinent.