Attorneys have asked me whether labs test for saliva, particularly in sexual assault cases. Dr. Maher “Max” Noureddine wrote the Forensic Tests for Saliva: What you should know post for this blog in 2011. His informative post explains how forensic tests for saliva work, including limitations of these tests. He discusses the RSID-Saliva test which tests for alpha-amylase found in saliva. This test should be considered presumptive in nature, since other bodily fluids including semen, urine, sweat, feces, vaginal secretions, and breastmilk can yield a positive result because they contain alpha-amylase.
Attorneys may be aware that the NC State Crime Laboratory previously used the RSID-Saliva test to test for saliva. In January 2017, the State Crime Lab stopped offering that test, per their Policy and Procedure for Evidence Submissions, Ver. 1 (see Section 3.15.1).
In cases involving evidence of saliva testing, attorneys should obtain expert assistance so that they can ensure needed data from the RSID reader has been preserved and is provided through discovery. Attorneys, with expert assistance, must also evaluate whether to challenge expert testimony on saliva under Rule 702 as either an unreliable methodology as a whole or as applied in a particular case. The IDS Forensic Resource Counsel can provide attorneys with additional information, assistance in drafting motions, and assistance in identifying experts.