The eyewitness testimony and identification of culprits are exposed to multiple factors and other negative effects. Errors can occur both in the phase of perception and interpretation of stimuli as well as in the phase of their processing, encoding in long term memory and later in their recall and recovery. Memory is not only exposed to external factors and the influence of individuals’ personal characteristics, such as age, race, influence of personal history, but also to other cognitive changes, processes of forgetting and distortion. The listed errors of perception and memory have no important significance in everyday life. They become problematic when the conclusions of the evidence procedure and thus its end depend on the content of memory recall. Experts in the field of psychology in collaboration with law enforcement personnel have developed techniques with which they try to influence the quality and quantity of recalled eyewitness memory data and hence the accurate testimony. These measures include a cognitive interview, an analysis of statement validity and the presence of an expert witness from the field of psychology in the court. Most importantly, also the crime investigators and judges who can with their knowledge greatly influence the way of obtaining eyewitness information, and who decide which evidence is sufficiently reliable and accurate to base their judgment on, must be well aware of the presence of mistakes and misconduct in the eyewitness testimony.