Disaster behavioral health is increasingly regarded as a central part of disaster preparedness, response and recovery. Legal and ethical issues have received relatively little attention and have sparked divergent opinions. Optimally, understanding and applying legal and ethical considerations requires an understanding of the evolution of the disaster behavioral health field and the context of disaster response and recovery. In addition, there are many legal and ethical questions identified for consideration, and many ways to approach reaching understanding and consensus. Traditionally, discussions of disaster behavioral health, including legal and ethical issues, have not included understanding decision making processes that occur in extreme circumstances. Models which interpret disaster response operations as complex adaptive systems are presented for consideration as useful tools for preparing mental health workers for effectively delivering services in acute disaster response environments.