When police find suspected illegal drugs on or near a suspect, they field test the substance as part of the determination of whether to arrest the suspect(s), to search further, or to seek a search warrant.

Unfortunately, positive drug field tests are so unreliable that generally they are inadmissible in evidence at a criminal drug possession trial, except that Virginia law, wrongfully, provides a method for prosecutors to offer such field test results into trial for marijuana possession cases. Va. Code § 19.2-188.1.

Drug field tests are sham science that often make the difference about whether a suspect gets arrested, denied a reasonable bond, and prosecuted. People deserve better than that.

Backing me up on this attack on drug field tests is a recent in-depth article by Ryan Gabrielson and Topher Sanders of ProPubica, in the New York Times.