This concise book brings behavioral insights to the wide array of topics commonly taught in the required professional responsibility course, including admission to the practice of law, confidentiality, conflicts of interest, representing entities, prosecutorial and criminal defense ethics, litigation and negotiation ethics, legal billing, and managerial and subordinate responsibilities. Behavioral legal ethics relies on empirical research to explore how lawyers actually make ethical decisions in context, rather than how they predict they would decide an ethical dilemma. This approach complements the law of lawyering by seeking to understand how various psychological factors and situational pressures explain and influence decision-making and resulting ethical (or unethical) action. Each chapter explores findings from behavioral science that pertain to ethical decision-making such as motivated reasoning, confirmation bias and other cognitive biases, fast thinking, the fundamental attribution error, wrongful obedience, conformity, moral disengagement, and much more. In addition, each chapter contains relevant case studies and reflection questions to deepen and cement students' understanding of the role of behavioral legal ethics in professional responsibility. Finally, the book offers ideas for individual attorneys and legal organizations to improve ethical decision-making. The book can be used as a stand-alone text in a required professional responsibility course, along with the ABA Model Rules of Professional Conduct and select cases and materials, or it can be used as a supplement to a professional responsibility casebook. In addition, the book can be used in advanced legal ethics courses. The authors, both scholars in the field of behavioral legal ethics, are professional responsibility professors who have incorporated behavioral legal ethics into their own classrooms. They have found that students enjoy studying and discussing behavioral insights, and that integrating a behavioral focus to the study of legal ethics helps students better understand the ethical doctrines, policy, and context that underlie the law of lawyering and the ABA Model Rules. A sampling of student testimonials include: "I found the psychology of legal ethics extremely helpful. It really allowed me to focus in on the issues I know I will be challenged with when I enter the legal profession." "I liked how the course was not just putting the rule on the board and going over it, which I have heard some professors do. I liked looking at the rules through a behavioral science lens." "I appreciated the unique take from the behavioral sciences side." "It is kind of hard to imagine studying ethics without any mention of the psychological issues at this point."