Approach helpful for differentiating hemp- and marijuana-derived plant products: A review

The legalization of hemp and the rapid growth of hemp-derived products have created major challenges for forensic and related laboratories in the United States. As marijuana remains illegal at the federal level and is heavily trafficked, accurately differentiating legal hemp from illicit marijuana is critical for law enforcement, industry, and medical applications. This review summarizes current methods used in cannabis classification, including morphological examination, chemical analysis, and genetic approaches, and discusses the limitations of each approach. Gas chromatography (GC)-based methods remain the primary technique in forensic laboratories due to their long-standing use in seized-drug analysis, efficiency, and cost-effectiveness. Liquid chromatography (LC)-based methods avoid thermal artifacts and allow the direct quantification of acidic and neutral cannabinoids. Other techniques, such as direct analysis in real time (DART) and spectroscopy, can also improve analytical efficiency. However, each approach has particular limitations, and the continuing emergence of hemp-derived cannabinoids interferes with analysis and interpretation. DNA-based approaches, for which synthase-gene markers, simple sequence repeat (SSR) markers, and organelle markers have been discovered and evaluated, can offer stable and environment-independent alternatives, yet their forensic implementation is limited by insufficient databases, assay complexity, and laboratory resource constraints. Continued development and method selection should be guided by laboratory resources and the intended application. It is important to understand the limitations and ensure careful evaluation and validation to support accurate and defensible cannabis testing.