As we will see below, psychology has a great influence on law and these two branches of science would be unthinkable in todays world without each other. They complement each other in many fields and are in constant interaction. Accordingly, today there is a special branch of science called forensic psychology. It deals with witness testimony as its most important part, and the subject of connecting these two sciences. The paper systematically describes forensic psychology from its very beginnings, its origin to the methods that are used today in this science when evaluating testimony. In the second part, psychology and law are described as separate scientific disciplines which, over time and under the influence of research and collaboration of scientists from both scientific disciplines, grow into a separate science, as a result of the need and progress in improving interpersonal relations and improving the legal and social order. In the third part entitled forensic psychology, its methods and their application, the methods used in modern times and without which the functioning of modern society and the legal system would be unthinkable today are listed and described. In the fourth part, called the characteristics of testimony, the basic concept of forensic psychology is described, which is witness testimony. In the fifth part, called the application of psychology in the evaluation of statements, the influences that can significantly change the witnesss perception of reality, as well as the scientists who contributed to these investigations, are listed. In the sixth part, some characteristics by which we can recognize a false statement to some extent are presented and its clear difference compared to a false statement is described. In the conclusion, the author presents his critical opinion on forensic psychology as a science and the importance of evidence in court proceedings, as well as the possibility of its development in the future.