Testing Marijuana in New Jersey

TestingIn New Jersey, the State’s chemists use two methods to determine if seized drug evidence is marijuana. These two testing methods are microscopic evaluation (microscopy) and color testing.

In the forensic science realm, testing methods are known as either “presumptive” or “confirmatory.” Presumptive testing only shows that a sample is certainly not a particular substance and what substance that sample probably is. In other words, presumptive testing is not conclusive and only gives the chemist certain information about the drug sample. Presumptive testing yields false positives, which may cause a sample to be misidentified. Microscopy and color testing are presumptive tests.

If a laboratory uses presumptive testing initially, it must use a confirmatory test to scientifically ensure that the sample is, in fact, the suspected substance shown through presumptive testing. Gas chromatography with mass spectrometry (GCMS) or liquid chromatography with mass spectrometry (LCMS) are two examples of confirmatory testing.


At this point, you should be asking why a state chemist would only use two presumptive tests and not a confirmatory test when testing suspected marijuana. That is a good question. It is one I cannot answer, since I am not privy to the decision making processes at the laboratories. However, I can state that this failure to engage in sound scientific testing provides many different attacks that an experienced, well-trained attorney will use to call lab results into question.