Judges are key in a common law legal system like England and Wales. However, how they arrive at their decisions may be a mystery to outside observers. This course seeks to shed light on this process. The course starts by explaining how judges make factual findings from evidence, how they choose how a case should be decided, and how they explain their thinking. The law is key to all these processes, influencing judges at every stage. To explain the role of the law, the course starts by focussing on the more straightforward cases where the law is certain. As the course progresses, it introduces the harder cases where the law is uncertain and examines how judges and lawyers navigate it. As the challenges of uncertainty are introduced, the course also looks at fundamental debates concerning judicial decision-making, in particular, the issues of representativeness of the judiciary, bias, and whether judges make law.