A system mobilization model with six paradigms is proposed. A perception paradigm produces awareness of matters that might be the subject of a conflict or dispute. Another paradigm explains how these detected matters are socially constructed as potentially legal matters; a legal-mobilization paradigm explains how legal agents or some legal subsystem is mobilized to handle some legal matters. A process paradigm explains how matters that enter the trial courts become matters for trial, and a trial-court mobilization paradigm is followed by an appellate-process paradigm. The development of such a model of system litigation will resolve some of the methodological as well as conceptual problems that currently beset research on trial courts. A number of these problems relating to the longitudinal study of trial courts are discussed. (Author abstract modified)