A descriptive model is proposed to explain major factors and specific variables that affect the need to use or likelihood of using force. The model depicts a police officer's behavior as the culmination of various influences and actions of others. Model components include antecedent events, traits and behaviors of parties, situational information and characteristics, police officer characteristics, available options, constraints and facilitative factors, and situational outcomes. The model can be used as a framework to organize findings from existing literature and interpreting their meaning. Given the increasingly litigious nature of police-citizen encounters, police officers must consider legalities and political ramifications of a selected action and make decisions accordingly. Perhaps the most critical consideration for a police officer in determining which behavior to select is his or her perception of whether the behavior may be questioned and who will support it. 16 references and 1 figure