Harvesting tall varieties for grain is difficult. In France, the principal grower of dual-purpose varieties, the grain is taken off the field first, leaving most of the stalks for later harvest (Fig. 49). Putting tall whole plants through a conventional combine results in the straw winding around moving parts, and the fibers working into bearings, causing breakdown, fires, high maintenance, and frustration. Following the French example of raising the cutting blade to harvest the grain is advisable. Growing short varieties dedicated to grain production eliminates many of the above problems, and since the profitability of hemp straw is limited at present, seems preferable. Grain growers should be aware that flocks of voracious birds are a considerable source of damage to hempseed, particularly in small plantations.
Marijuana is the most common illegal drug reported in motor vehicle accidents. A 2012 meta-analysis found that cannabis use was associated with an increased risk of being involved in a motor vehicle crash. A 2016 review also found a statistically significant increase in crash risk associated with marijuana use, but noted that this risk was "of low to medium magnitude." The increase in risk of motor vehicle crash for cannabis use is between 2 and 3 times relative to baseline, whereas that for comparable doses of alcohol is between 6 and 15 times.
In the United States, the legality of medical marijuana varies in substantial ways from state to state. There are currently 29 US states with legal medical cannabis laws, as well as the District of Columbia. That leaves 21 states where medical marijuana is entirely prohibited. Marijuana cultivation, possession, and use in any form is illegal at the federal level.
Since the beginning of the 20th century, most countries have enacted laws against the cultivation, possession or transfer of cannabis. These laws have impacted adversely on cannabis cultivation for non-recreational purposes, but there are many regions where handling of cannabis is legal or licensed. Many jurisdictions have lessened the penalties for possession of small quantities of cannabis so that it is punished by confiscation and sometimes a fine, rather than imprisonment, focusing more on those who traffic the drug on the black market.
On the other hand, marijuana-derived CBD and anything else derived from a cannabis plant was still classified by the DEA as a Schedule I drug (defined as a drug with "no currently accepted medical use and a high potential for abuse") until October 2018. In 2016, the DEA stated that all extracts containing more than one cannabinoid would remain classified as Schedule I. However, the approval of Epidiolex had an influence in changing this, and prescription CBD drugs with a THC content of below 0.1% have now been reclassified as Schedule 5, the lowest rating.
Several studies have demonstrated the therapeutic effects of cannabinoids for nausea and vomiting in the advanced stages of illnesses such as cancer and AIDS. Dronabinol (tetrahydrocannabinol) has been available by prescription for more than a decade in the USA. Other therapeutic uses of cannabinoids are being demonstrated by controlled studies, including treatment of asthma and glaucoma, as an antidepressant, appetite stimulant, anticonvulsant and anti-spasmodic, research in this area should continue. For example, more basic research on the central and peripheral mechanisms of the effects of cannabinoids on gastrointestinal function may improve the ability to alleviate nausea and emesis. More research is needed on the basic neuropharmacology of THC and other cannabinoids so that better therapeutic agents can be found.
In the Australian states of Tasmania, Victoria, Queensland, and most recently, New South Wales, the state governments have issued licences to grow hemp for industrial use. The first to initiate modern research into the potential of cannabis was the state of Tasmania, which pioneered the licensing of hemp during the early 1990s. The state of Victoria was an early adopter in 1998, and has reissued the regulation in 2008.
Only a handful of countries have legalized recreational marijuana. Uruguay was one of the first, in 2013. The Netherlands is perhaps the country most known for legal marijuana, yet the drug is illegal there. Spain has given its citizens the rights to grow and consume cannabis privately. Peru also allows citizens to possess marijuana as long as it is for personal, private use. As in Costa Rica, where people can have a “small amount,” without legal trouble.