For years, people have used the words “hemp” and “marijuana” as if they were different plants. Legally, though, the gap between them comes down to one number on a lab report and what that number triggers under U.S. law.
At the federal level, both hemp and marijuana come from the same species, Cannabis sativa L. The 2018 Farm Bill created a new legal category of “hemp,” defining it as any part of the cannabis plant—including seeds, extracts, and cannabinoids—that contains no more than 0.3% delta-9 THC by dry weight. Anything above that threshold is no longer hemp under federal law; it is marijuana. This definition is now written into federal agricultural law and regulations that govern hemp cultivation and testing.
The Farm Bill did more than split cannabis into two categories. It also removed hemp from the definition of “marijuana” in the federal Controlled Substances Act. Before 2018, all cannabis, regardless of THC level, was treated as marijuana and classified as a Schedule I controlled substance. Today, hemp is treated as an agricultural commodity, while marijuana remains a federally illegal drug with a high potential for abuse and no accepted medical use under federal scheduling.
This legal line has consequences for how products are regulated. Hemp and hemp-derived ingredients like CBD can be grown for interstate commerce if producers follow federal and state hemp programs, including licensing and THC testing rules. By contrast, marijuana and marijuana-derived products cannot cross state lines and are regulated under stricter drug control and state cannabis laws, even where voters have legalized adult-use or medical markets.
The 0.3% limit also matters over the life of a product. If a manufacturer starts with hemp that meets the federal definition but concentrates THC during processing so that the final material exceeds 0.3% delta-9 THC on a dry-weight basis, it is no longer legally hemp. At that point it may be treated as marijuana and subject to federal drug rules, including potential DEA registration requirements for handling and research. Regulators have made clear that “hemp” status does not automatically follow a product if its THC level increases during manufacturing.
Recent federal action has tightened rules around intoxicating hemp-derived products. Congress has moved to close loopholes that allowed the sale of psychoactive cannabinoids like delta-8 THC and high-potency THC beverages outside state-regulated marijuana systems. New legislation keeps the 0.3% THC definition for hemp but bans many synthesized or highly concentrated THC products and places strict limits on total THC per package, changes that are expected to reshape the hemp-derived THC market.
Layered on top of federal law are state rules, which can be more permissive or more restrictive. Some states allow hemp-derived products with low doses of THC but prohibit intoxicating hemp variants; others limit smokable hemp or certain edibles. Meanwhile, state marijuana programs regulate cultivation, processing, and retail sales for higher-THC cannabis, often with their own potency caps, testing standards, and packaging rules.
For consumers, the legal difference between hemp and marijuana is not a mere technical detail. It helps determine where a product can be sold, whether it can be shipped across state lines, what kind of testing and labeling it must undergo, and what risks come with possession or use. As lawmakers keep adjusting hemp and marijuana laws, that 0.3% number on a certificate of analysis will act as the dividing line between an agricultural crop and a controlled substance.