The National Judicial College and the Justice Speakers Institute, LLC developed this bench book with support from the State Justice Institute to help judges determine the admissibility of evidence based on sound forensic science. The fact is, few judges were scientists in a previous career. The scientific method is not second nature to most, and few subscribe to scientific journals. In a worst-case scenario, a judge could admit so-called “scientific testimony” even after the scientific community had discredited it. This first-of-its kind book for state court judges is a practical guide to the key types of scientific evidence judges are likely to encounter on the bench. It is the work of expert judges and practitioners. All judges, new or experienced, will find it helpful when considering complex scientific evidence.