Nearly every agency in Georgia uses the Duquenois-Levine test as a screening agent for THC, the active ingredient in marijuana. The test is cheap, easily stored, and even recognized as scientific to prove that a substance is marijuana in the State of Georgia. See Cunrod v. State, 241 Ga. App. 743 (2000). The reagent has been around for approximately seventy years (strange to imagine people smoking the stuff seventy years ago). Our Georgia Court of Appeals approves of this test as scientific at a criminal trial.
The test does react to THC, but it also reacts to other things including Hershey's Dark Chocolate Kisses, plain chocolate M&Ms, and shavings from Thin Mint Girl Scount cookies.
In fact, the test shows positive for THC with Cocoa Puffs (not saying it's coo coo).
Well, on sight, it would be difficult to confuse marijuana with chocolate. The KN reagent test, another popular screening tool, also tests positive for oregano and thyme.
Of couse, you might also think that, since these tests are just used in the field, there is not much risk of a misidentification. However, Georgia does not require any further testing for marijuana other than microscopic examination, the fast blue salts test, and the D-L test.
Further testing is done at the GBI crime lab, but the turnaround can be months. During those months, a defendant may be held without bond and under the cloud of suspicion for being charged with a drug offense. Unfortuntately, there is no screening tool to give you your reputation back.
For more on chocolate and THC see the April edition of The Champion, NACDL's magazine.