Gister-CL implements a suite of evidential reasoning techniques that can be used during plan generation and plan execution to analyze uncertain information about the world and possible actions [12]. The techniques are based upon the mathematics of belief functions developed by Dempster and Shafer [11] and have been successfully applied to a variety of problem domains. Gister-CL supports the construction, modification, and interrogation of evidential structures, thereby allowing a domain expert to quickly and flexibly develop an argument (i.e., a line of reasoning) specific to a given situation.