This book initially takes a snapshot of the state of the art in the legal sciences regarding witness testimony, both in the doctrine and case law of various countries. Essentially, in this first part, the book tries to show that the law usually deals with witness testimony from two mistaken premises: from the idea that the witness either tells the truth or lies, ignoring honest mistakes; and from the idea that fact-finders or others who receive testimony would be able to detect lies. In the second part, the book initially looks to the epistemology of testimony as a basis for disproving the idea that testimony should be presumed true when there is no evidence to the contrary. Subsequently, using rigorous scientific methodology to search for empirical studies, the text identifies what science has consolidated in recent decades as knowledge about the functioning of perception, memory storage and retrieval. Basically, this part demonstrates the existence of honest mistakes, with their numerous scientifically proven sources (passage of time, post-event information, ways of asking questions, weapon focus effect, etc.), and the inability of human beings to detect lies. In the third and final part, once the premises on which legal systems are normally based have been shown to be false, the text presents proposals, both theoretical and practical, the latter aimed at each subject involved in the admission, production and evaluation of witness testimony (judges, lawyers, prosecutors, witnesses, etc.).
