This chapter examines the fundamental ways in which human cognitive functions, such as memory, attention, perception, reasoning, and communication, affect the decisions, reasoning, and behavior of all parties involved in the legal system. For example, since human memory is a dynamic, error-prone reconstructive process rather than a recording mechanism it can affect legal decisions. This calls into doubt the validity of eyewitness testimony in court settings. Event nature, post-event information, individual characteristics, and retrieval method are important aspects that impact memory. The chapter next looks at the proper methods for a cognitively aware investigator. They employ the same thought processes as laypeople. Their thinking is guided by mental models and inferential reasoning. Furthermore, cognitive and emotion biases often affect also professional reasoning and decision-making. Effective investigative interviewing, empathic communication and lie detection techniques are then introduced. Another important cognitive aspect to be considered in legal context is narration. People naturally tell stories, and legal procedures are greatly influenced by narrative thinking. People often add connecting details and eliminate contradictory details to create internally coherent narratives. A tale that makes sense is frequently taken for fact. The chapter contrasts the narrative approach (where the order and emotional/moral context of information matter) with the Bayesian approach (which integrates objective information quantitatively). The narrative approach can foster empathy and understanding but may also introduce subjectivity and bias. After discussing a case study, the chapter ends with the concept of Creativity. Creative thinking is a vital but underutilized tool in legal practice. Creativity helps in reframing problems, finding common ground in negotiations, breaking cognitive fixedness, and developing novel legal strategies. However, Creativity must be used appropriately, as it can be time-consuming and may be perceived as disruptive or aggressive in certain legal contexts.