Errors in computer output can arise from a number of sources. The hardware or software may be faulty or may develop faults when interacting with other components in a particular computer network; the hardware may develop faults because it is working in an unsuitable environment; the software may be inadequately tested and contain hidden errors; faults may be produced by telecommunication lines used for transmission of data between computers in a network; and users may be inadequately trained. At least three issues should be considered in determining the admissibility of computer evidence: (1) whether the computer evidence is hearsay or real and whether it is admissible as one of the exceptions to the hearsay rule; (2) whether the computer evidence is reliable; and (3) whether the evidence presented is the 'best evidence' that can be obtained from the computer. Four courtroom dramas are portrayed to illustrate and illuminate problems that beset lawyers and computer professionals in dealing with computer evidence. The cases demonstrate the complexities of the law and explain the technical jargon of computing so nonspecialists can understand the concepts. The appendixes discuss computer basics and special crimes made possible by computer technology. Ten bibliographic listings are provided.