The misguided soldiers of the American drug war are infamous for employing a cornucopia of barely legal sabotage tactics in order to sucker the unsuspecting citizen into a roadside shakedown. One of the most underhanded methods the police use to establish probable cause is claiming to smell marijuana in a vehicle, which according to legal experts should be ruled unconstitutional because the skunk odor associated with cannabis is not exclusive to the plant.
In fact, a study entitled “Marijuana Odor Perception: Studies Modeled From Probable Cause Cases,” which was published in a 2004 edition of the journal Law and Human Behavior, suggests many common plants and some animals have scents identical to marijuana, making it an inaccuracy for an officer to establish probable cause based on his claim of smelling weed.
“Although law enforcement officials routinely rely solely on the sense of smell to justify probable cause when entering vehicles and dwellings to search for illicit drugs, the accuracy of their perception in this regard has rarely been questioned and, to our knowledge, never tested,” wrote the study authors.
Humans are not equipped with a strong enough olfaction to detect certain odors, much less properly distinguish a stinky culprit from a combination of smells. The perfect scenario, for example, is the reason everyone knows it is always safer to fart in a crowded room rather than a space only containing two people. The average person simply cannot pinpoint the origin of the smell without literally burying their nose in the suspected source, or by process of elimination.
This is the reason law enforcement agencies employ the use of drug-sniffing dogs. These four-legged beasts not only have the schnauzer power to track down very specific fumes, but they can also do it very efficiently. And, unlike humans, canines cannot be bamboozled with masking odors because they smell items separately. A prime example of this is vegetable soup: while humans simply smell soup, a dog smells peas, carrots, potatoes, etc.
However, the odor of marijuana is created by more than 200 different terpinoids, which are also found in many other things: the scent of a skunk, marigolds, hops, and even certain variations of decomposing trash – all items that could even fool a drug-sniffing dog into thinking that he just stumbled onto a fat stash of reefer.
If terpenes can throw off a dog’s impeccable sense of smell, it stands to reason that the nose of a police officer is either often fooled, or they just use the suspected odor of marijuana as an excuse to conduct a search. The study authors suggest the latter.
“The present findings throw into question, in two specific instances, the validity of observations made by law enforcement officers using the sense of smell to discern the presence of marijuana. Although these instances reflect a very small set of studies with very specific constraints, they do suggest that a blanket acceptance of testimony based upon reported detection of odors for probable cause is questionable and that empirical data to support or refute such testimony in specific cases is sorely needed.”
Unfortunately, while sense of smell is nowhere near a scientific or accurate method for establishing probable cause, many courts have ruled in favor of the pig’s snout.