How Different Is Different? Arguing About the Significance of Similarities and Differences

Our instructional program, CATO, uses a model of case-based legal argument to teach law students basic skills of making arguments with cases. CATO represents abstract knowledge about the meaning of the similarities and differences between cases in a Factor Hierarchy, in which the ‘factors’ used to represent case facts are linked to higher level concerns and legal issues. The Factor Hierarchy enables CATO to identify issues in a problem and to organize multicase arguments by issues. The Factor Hierarchy also helps to assess and explain the importance of differences in terms of more abstract knowledge, yet in a manner sensitive to the context of the particular problem and case being compared and the argument for which the comparison is made. We evaluated CATO in a controlled experiment, comparing 7.5 hours of CATO instruction to classroom instruction led by an experienced legal writing instructor. The results indicate that the CATO instruction led to significant improvement in students’ basic argument skills, comparable to that achieved by the legal writing instructor. We also found that more is needed in order for CATO to prepare students for a more advanced and complex memo writing task.