Under all too familiar circumstances, medical malpractice cases will come to trial with issues based in evidence that had long been forgotten. The claims important at trial have emerged over the course of months to years of pretrial proceedings, during which the same medical procedures were repeated hundreds if not thousands of times. There are instances in which the participants in those medical procedures know what happened even if they do not specifically recall it. Courts and counsel need to be prepared to identify those instances when testimony on custom and habit is admissible and who can provide it.