Marijuana prohibition has been in effect since 1937, with similar affects to alcohol prohibition. An increase in crime, distrust and disharmony. If the aim of marijuana prohibition is to stop people from using it, then it has failed. Just like alcohol prohibition failed at the time. Simply saying it is bad for you and you will be charged is not enough to stop people from doing it. If anything more people may use to be rebellious and let their hair down. To buck the system.
People need to be educated as to the affects of marijuana. Then in my opinion it should be up to them based on the information whether they wish to use marijuana. Unlike heavy drugs like cocaine and heroine which should be strictly prohibited. Although people still need to be educated.
Different places in the world have different laws. These range from criminal penalties with court appearance to misdemeanours with small fines.
