Scientifically, the difference between what we refer to as hemp and marijuana comes from the intention the strain was bred for. The main difference between hemp and marijuana is the level of THC in the plant. Hemp has high levels of cannabidiol (CBD) and very low levels of tetrahydrocannabinol (THC). Marijuana is recognized for having high levels of THC and lower in CBD. In order to be considered hemp, the plant must have less than 0.3 percent THC. High levels of THC are responsible for the intoxicating feeling that marijuana is known for.
Cannabidiol is currently a class B1 controlled drug in New Zealand under the Misuse of Drugs Act. It is also a prescription medicine under the Medicines Act. In 2017 the rules were changed so that anyone wanting to use it could go to the Health Ministry for approval. Prior to this, the only way to obtain a prescription was to seek the personal approval of the Minister of Health.