The adoption of econometric procedures designed to test between alternative forms of dynamic equilibria, indicated that from 1946 to 1985 there was a steady growth rate in prison admissions, and that rising unemployment was an important contributing factor. Based on a behavioral model of judicial expectations, it is argued further that judges used their expectations as heuristic devices for simplifying sentencing decisions. Unanticipated changes in unemployment caused corresponding changes in sentencing patterns underscoring a need for better information. Guidelines need to be set to restrict the use of extralegal factors in the administration of justice. Findings coincide with those of other British researchers in that unemployment plays a much larger role in determining prison sentences than under Anglo-American legal traditions. 2 graphs, 3 tables, 60 references. (Author abstract modified)