The case method is a teaching approach that uses decision-forcing cases to put students in the role of people who were faced with difficult decisions at some point in the past. It developed during the course of the twentieth-century from its origins in the casebook method of teaching law pioneered by Harvard legal scholar Christopher C. Langdell. In sharp contrast to many other teaching methods, the case method requires that instructors refrain from providing their own opinions about the decisions in question. Rather, the chief task of instructors who use the case method is asking students to devise, describe, and defend solutions to the problems presented by each case.

The case method evolved from the casebook method, a mode of teaching based on Socratic principles pioneered at Harvard Law School by Christopher C. Langdell. Like the casebook method the case method calls upon students to take on the role of an actual person faced with a difficult problem.

A decision-forcing case is a kind of decision game. Like any other kinds of decision games, a decision-forcing case puts students in a role of person faced with a problem (often called the "protagonist") and asks them to devise, defend, discuss, and refine solutions to that problem. However, in sharp contrast to decision games that contain fictional elements, decision-forcing cases are based entirely upon reliable descriptions of real events.

A decision-forcing case is also a kind of case study. That is, it is an examination of an incident that took place at some time in the past. However, in contrast to a retrospective case study, which provides a complete description of the events in question, a decision-forcing case is based upon an "interrupted narrative." This is an account that stops whenever the protagonist finds himself faced with an important decision. In other words, while retrospective case studies ask students to analyze past decisions with the aid of hindsight, decision-forcing cases ask students to engage problems prospectively.

After corporate scandals and the 2008 financial crisis, the case method was criticized for contributing to a narrow, instrumental, amoral, managerial perspective on business where making decisions which maximise profit is all that matters, ignoring the social responsibilities of organisations. It is argued that the case method puts too much emphasis on taking action and not enough on thoughtful reflection to see things from different perspectives. It has been suggested that different approaches to case writing, that do not put students in the ‘shoes’ of a manager, be encouraged to address these concerns.

Every decision-forcing case has a protagonist, the historical person who was faced with the problem or problem that students are asked to solve. Thus, in engaging these problems, students necessarily engage in some degree of role play.

Some case teachers, such as those of the Marine Corps University, place a great deal of emphasis on role play, to the point of addressing each student with the name and titles of the protagonist of the case. (A student playing the role of a king, for example, is asked "Your Majesty, what are your orders?") Other case teachers, such as those at the Harvard Business School, place less emphasis on role play, asking students "what would you do if you were the protagonist of the case."

After discussing student solutions to the problem at the heart of a decision-forcing case, a case teacher will often provide a description of the historical solution, that is, the decision made by the protagonist of the case. Also known as "the rest of the story", "the epilogue", or (particularly at Harvard University) "the 'B' case", the description of the historical solution can take the form of a printed article, a video, a slide presentation, a short lecture, or even an appearance by the protagonist.