We are very pleased that we have been asked to contribute an updated chapter on legal principles for this volume. 1 As we noted in the original chapter, many principles of employee selection have been illuminated through decades of equal employment opportunity legislation, regulation, and related case law. Granted, judges write opinions, but these judges frequently depend heavily on industrial-organizational (I-O) psychologists in framing these opinions and are generous in their citations to our work and our testimony. Once again, we see a clear role for employment litigation knowledge related to personnel selection in this volume.