The fairness of the judicial process depends on the objective presentation of facts to an impartial jury made up of one's peers. Present the facts, and you have a fair trial. However, fact-finding, especially for interpersonal disagreements, is not so straightforward and is often contaminated by variables that reach beyond the legal domain. A trial is an attempt to transport jurors to the time and place of the disputed event, to recreate the disputed event, or at least to explain that event with maximum accuracy. A trial falls short of this goal, however, because it presents selected witnesses who recite selected portions of their respective memories concerning selected observations of the disputed event. These multiple selections are referred to as the abstraction process. Limitations in both perception and memory are responsible for the fact that the remembered event contains only a fraction of the detail present during the actual event, and the delay between observation and recitation causes witnesses' memories to lose even more of the original perceptions. During the course of a trial, a witness's recitation of the now-abstracted events may reflect selected disclosure based on his or her attitudes and motivations surrounding that testimony. Furthermore, the incidents reported are dependent on the lines of inquiry established by the attorneys involved. Accordingly, the recited data are a fraction of the remembered data, which are a fraction of the observed data, which are a fraction of the total data for the event. After the event that led to the trial has been abstracted by participants in the trial, jurors are expected to resolve factual issues. Some of the jurors' conclusions are based on facts that were directly recited; others are found inferentially. Here another abstraction process takes place. Discussions during deliberations add to the collective pool of recalled evidentiary perceptions; nonetheless, the jurors' abstraction processes further reduce the number of characteristics traceable to the original event. Complication can arise from false abstractions at each stage. Studies have shown that witnesses recall having perceived incidents that are known to be absent from a given event. Conversely, jurors can remember hearing evidence that is unaccounted for in court transcripts. Explanations for these phenomena range from bias through prior conditioning or observer expectation to faulty reportage of the event based on the constraints of language. Aberrant abstractions in perception or recollection may not be conscious or deliberate, but reliability is nevertheless diluted. Finally, deliberate untruthfulness has always been recognized as a risk of testimonial evidence. Such intentionally false abstractions, however, are only a small part of the inaccuracies produced by the abstraction process.