Canada will be named as a nation in which we can use recreational marijuana legally.
The federal government has decided to legalize the use and sale of marijuana for the recreational purpose by 2018. So far, legal use of marijuana is limited to only medical end. Under the new legislation, a detailed guideline for sale of marijuana will be published. Each provincial government will be able to set a regulation of the age for buying marijuana.
The Guardian: Canada introduces long-awaited legislation to fully legalise marijuana
This legislation seems to have been established for an urgent need of public health. Currently, as the trade of marijuana is prohibited, people rely on the criminal organization for getting marijuana. It is easily estimated that marijuana is one of the core financial sources for antisocial groups. Decriminalized marijuana will lead to the reduced income of such organizations. This structure is mirroring anti-alcohol law in the US.
However, the risk of marijuana to cause mental illnesses is underestimated, I am afraid. Indeed, marijuana is rather a harmless drug among psychotropic substances. Nonetheless, there are patients who are suffering from marijuana psychosis. In the UK, as cannabis use is spread over the country, medical practitioners are enthusiastic to treat the patients to guide them to the life without psychotropic drugs.
In Japan, even medical marijuana is not legalized. Recently, a person who had been suffering from chronic pain was arrested on cultivating marijuana personally. He claimed that he needed marijuana for life free from the pain, so taking marijuana is the human right. The court decision has not been fixed.
In my opinion, medical use of marijuana should be legalized. On the other hand, decriminalizing recreational marijuana is considered with great caution. Even if you do not become psychotic after taking marijuana, it will get rid of your productivity. In Canada, as well as other countries where marijuana has already become familiar, legalization and moderate governmental control of marijuana is a rational option. But generally speaking, I do not agree with the legalization of sucstance with dependency.