The National Research Council and Federal Judicial center last week released the new edition of the Reference Manual on Scientific Evidence. Readers of MassTortDefense know about this manual as a guide for judges searching for effective and fair ways to handle science-based issues, including assessing expert testimony. The Supreme Court has made clear that the law imposes on trial judges the duty, with respect to scientific evidence, to become evidentiary gatekeepers. The judge, without interfering with the jury’s role as trier of fact, must determine whether purported scientific evidence is “reliable” and will “assist the trier of fact,” thereby keeping from juries testimony that lacks the same level of intellectual rigor that characterizes the practice of an expert in the relevant field.