"QUESTION: Is DNA evidence routinely admissible at trial?
ANSWER: Yes. Most judges today accept expert evidence based on DNA analysis. The universally-accepted theory underlying DNA analysis is that every person (except an identical twin) has a unique molecular makeup. Different methodologies allow experts to identify the portions of DNA molecules that establish a person's uniqueness. The most common of these methodologies is RFLP, or the Restriction Fragment Length Polymorphism Technique. By comparing an individual's known DNA with a sample of DNA from a crime scene (for example, in a droplet of blood or a strand of hair), an expert can give an opinion concerning the likelihood that both samples came from the same individual." -From, "The Criminal Law Handbook" By: Bergman & Berman-Barrett