...For years, despite lacking a proper scientific foundation, many forensic practitioners have offered either unvalidated evidence or grossly exaggerated the value of the evidence, particularly in forensic disciplines that examined pattern, impression and trace evidence, e.g comparison of bite marks, shoe prints, bullets and hair.
The National Academy of Science acknowledged this problem in 2009, concluding that “with the exception of D.N.A., no forensic method has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source.”
The problem, however, will not be cured by reliance on D.N.A. testing for most cases, there is no biology to test. But the other forensic disciplines never underwent the extensive basic and applied research, voluminous peer review and Food and Drug Administration approval because, unlike D.N.A., they never had a clinical application. They were primarily developed by law enforcement solely for criminal investigation.