People should be allowed to do whatever they want to their own bodies  It is important that we have the liberty to do what we want to our own bodies. People are allowed to eat or drink to their detriment. In many countries it is legal to take one's life. Why then, should people not be allowed to harm themselves through cannabis use? (Assuming that cannabis use is harmful. In most cases, this is highly debatable.)  Smoking cannabis may have effects on others, such as through the effects of passive smoking. However, regulation has been brought in to minimize the effects on others for alcohol and cigarettes, such as bans on smoking in public places, and the same thing could be done for cannabis.