Prohibition of drugs
While some drugs are illegal to possess, many governments regulate the manufacture, distribution, marketing, sale, and use of certain drugs, for instance through a prescription system. For example, amphetamines may be legal to possess if a doctor has prescribed them; otherwise, possession or sale of the drug is typically a criminal offense. Only certain drugs are banned with a "blanket prohibition" against all possession or use (e.g., LSD). The most widely banned substances include psychoactive drugs, although blanket prohibition also extends to some steroids and other drugs. Many governments do not criminalize the possession of a limited quantity of certain drugs for personal use, while still prohibiting their sale or manufacture, or possession in large quantities. Some laws (or judicial practice) set a specific volume of a particular drug, above which is considered ipso jure to be evidence of trafficking or sale of the drug.
Some Islamic countries prohibit the use of alcohol (see list of countries with alcohol prohibition). Many governments levy a sin tax on alcohol and tobacco products, and restrict alcohol and tobacco from being sold or gifted to a minor. Other common restrictions include bans on outdoor drinking and indoor smoking. In the early 20th century, many countries had alcohol prohibition. These include the United States (1920–1933), Finland (1919–1932), Norway (1916–1927), Canada (1901–1948), Iceland (1915–1922) and the Russian Empire/USSR (1914–1925). In fact, the first international treaty to control a psychoactive substance adopted in 1890 actually concerned alcoholic beverages (Brussels Conference). The first treaty on opium only arrived two decades later, in 1912.