Cannabis is a plant genus, and a variety of psychoactive products derived from these plants, including marijuana and hashish.
The legality of cannabis varies between countries. In many countries usage and possession of any amount are illegal, and enforcement might be strict. Other countries criminalize cannabis trafficking, but do not punish users. In a few countries and territories, the whole production and consumption chain of cannabis is legal for medical and/or recreational use.
Border controls on drugs are generally stringent. This includes borders within the United States of America, where neighboring states might have different drug laws, and even when they have the same laws, bringing cannabis from one state to another violates Federal drug trafficking laws.
- India: While cannabis remains illegal in India, some traditional forms of usage are allowed. One of them is bhang thandai, also known as bhang lassi, an infusion of cannabis paste (buds and leaves) and various nuts, herbs and spices in milk that is available in government authorised shops in parts of the subcontinent, including the states of Rajasthan, Uttar Pradesh, and Bihar.
- Netherlands: While technically never legalized, cannabis in addition to a handful of other substances disallowed elsewhere can be bought in "coffee shops" that are legal. The issue of "drug-tourism", however, is somewhat controversial so there may be some restrictions on foreigners frequenting coffee shops or buying cannabis products there. Cannabis products with no THC content are legal even outside coffee shops.
- Uruguay: While cannabis products are fully legal in Uruguay, the law states that buyers have to be over 18 and legal residents of Uruguay.
- United States: Several states have legalized use and/or possession of cannabis. While federal law prohibits possession, federal authorities do not currently pursue users who abide by state laws. Alaska, Washington, Oregon, California, Nevada, Colorado, Massachusetts, Maine, and Washington, D.C. currently allow cannabis for recreational use and several more have "medical marijuana" laws of varying strictness. As the constitution explicitly grants the federal government the right to regulate interstate commerce, carrying cannabis across state lines - even between two states where it is both legal - is a federal matter and illegal. Cannabis possession is likewise illegal on some Indian Reservations and all federal enclaves even when surrounded by states where it is otherwise legal.
- Canada: Medical marijuana has been legal for some time, with restrictions that vary from province to province. Full legalization was one of Justin Trudeau's campaign promises and he became Prime Minister in October 2015, but as of January 2017, he has not brought in legislation to legalize, only appointed a commission to work out the details.
In addition to places where marijuana is legal, there are several places where it is decriminalized, de jure or de facto. This may reach from an internal police memo declaring non violent cannabis consumers the "lowest priority" to more or less formal systems where cannabis is legal in all but name. The situation may sometimes vary drastically from subnational entity to subnational entity (the de facto limit for "personal consumption" in Berlin is much higher than in Bavaria for instance and the police in Bavaria are much more eager to open cases even for personal consumption, even if such evidence is routinely dismissed in court) and in some places even from city to city. Decriminalization might be practiced in various ways; in some cases the authorities confiscate drugs and smoking equipment, without a crime report.
The recent global trend has been one towards increasing legalization/decriminalization, but there is still a United Nations agreement that most sovereign states are parties to that classifies marijuana and hashish as controlled substances to be made illegal and combated. Many countries feel still bound by this convention, even if their actual policy is one of de facto decriminalization and laissez-faire. These jurisdictions might still criminalize imports and exports, as well as possession of quantities for more than personal use. The issue of "drug tourism" is a contentious one and most jurisdictions where consumption is legal at least in theory want to discourage people from outside the jurisdiction from visiting just for the consumption of cannabis products.
Some states where consumption of cannabis is illegal might penalize a positive urine or blood sample. These laws might cause trouble to a traveller who consumed the drug where it was not a crime. There are usually DUI laws that apply to cannabis, however legal limits for THC are much less publicized than those for ethanol and some jurisdictions have taken trace amounts of THC in the bloodstream, which - according to current medical consensus - have no impact on driving ability, as grounds for a driving ban and/or fine.
Some of the reported adverse health effects of cannabis are still under debate. The safest choice for many people is not to use the drug at all. Smoking any organic substance can release carcinogenic substances as well as harmful carbon monoxide (depending more on the temperature of combustion than the substance itself), so other avenues of consumption are much healthier for the lungs though not risk free either. As for smoking of other substances, there is also a fire risk.
Cannabis bought on the black market does not only raise legal concerns; it might include impurities which are much more dangerous than the cannabis itself. Furthermore there is obviously no legal recourse for bad quality, lower than advertised quantity or any other problem coming from black market dealings.
Cannabis use is also associated with a higher risk of psychosis and schizophrenia, particularly for people with a pre-existing genetic vulnerability. Although there is some scientific discussion about the exact link between cannabis and psychiatric illness, health organisations (also in countries where cannabis is legalized) typically warn against cannabis use for those with a history of psychosis. They also urge users to take extra care if there are cases of mental illness in their family or if they react unusually strongly (e.g. feel very disoriented or panic) after using cannabis.
Aside from the physical health effects, intoxication impairs sensory perception and judgment, and might be dangerous and illegal when driving. It also increases the risk of becoming a victim of a crime.
Even in countries where cannabis smoking or intoxication is not a crime, it might be prohibited, or unwelcome, at some premises. As for tobacco, think and ask before lighting up.