Part III presents the cooperative game theory in legal context and it contains two chapters: this chapter and Chap.  6 . This chapter introduces the basic principles of the cooperative game theory in legal context and guides the reader through modeling problems and solving them. This chapter explains how to model a problem through coalitional games with explanations on, inter alia, coalitions, null players, veto players, dictators, symmetric players, revenue games, cost games and the glove game. This chapter also explains how to solve legal problems using non-cooperative game theory with explanations, inter alia, on the different types of solutions, the core solutions and the Shapley value solution.