NIST urges caution in use of courtroom evidence presentation method
Courtroom use of ‘Likelihood Ratio’ not consistently supported by scientific reasoning approach, say NIST experts
Two experts at the National Institute of Standards and Technology (NIST) are calling into question a method of presenting evidence in courtrooms, arguing that it risks allowing personal preference to creep into expert testimony and potentially distorts evidence for a jury.
The method involves the use of Likelihood Ratio (LR), a statistical tool that gives experts a shorthand way to communicate their assessment of how strongly forensic evidence, such as a fingerprint or DNA sample, can be tied to a suspect.
In essence, LR allows a forensics expert to boil down a potentially complicated set of circumstances into a number–providing a…