Whether or not odor is sufficient enough for probable cause to start a search, warranted or warrantless, is often raised and debated in the court system. A person's ability to recognize a scent is very subjective. But the molecules responsible for odor, terpenes, are present in marijuana like many other plants. Determining the terpene signature, and showing the uniqueness of the terpene signature, can offer objective evidence that the odor of marijuana is unique. The fundamental issue here is whether the odor of marijuana, as perceived by a law enforcement officer, is sufficient to constitute probable cause for a further search or arrest. Probable cause is a rather low bar to be crossed, but is a bar that cannot be ignored and must be satisfied for a criminal case to proceed. The present study contributes to meeting and enforcing that bar.

This study has investigated the relative terpene signatures of marijuana in comparison to catnip, tobacco, oregano, and the closest plant relative of marijuana, hops. Using the AccuTOF™ DART™ Mass Spectrometer, the samples were analyzed both directly and indirectly. To analyze indirectly, samples were held adjacent to the sample airstream of the mass spectrometer and a gentle heat source was applied. Resulting spectra of the volatiles were compared. All samples gave different spectra signatures for their volatiles. The odor profile of marijuana is distinct from hops and any other plants commonly used as mimics for marijuana.