Uruguay has become the first country to legalise the growing, sale and smoking of marijuana in a pioneering social experiment that will be watched closely by other nations debating drug liberalisation.
A government-sponsored bill approved by 16-13 votes in the Uruguayan Senate provides for regulation of the cultivation, distribution and consumption of marijuana. It is aimed at removing the business from criminals in the small South American nation.
Backers of the law, some smoking marijuana, gathered near the Congress holding green balloons, Jamaican flags in homage to Bob Marley and a sign saying: "Cultivating freedom, Uruguay grows".
Cannabis consumers will be able to buy a maximum of 40 grams of the drug each month from licensed pharmacies as long as they are Uruguayan residents over the age of 18 and registered on a government database that will monitor their purchases.
When the law is implemented in 120 days, Uruguayans will be able to grow six marijuana plants in their homes a year, or as much as 480 grams, and form smoking clubs of 15 to 45 members which can grow up to 99 plants a year.
Registered drug users should be able to buy marijuana over the counter from licensed pharmacies in April.
"We begin a new experience in April. It involves a big cultural change that focuses on public health and the fight against drug trafficking," Uruguay's first lady, Senator Lucía Topolansky said.
Uruguay's attempt to quell drug trafficking is being followed closely in Latin America where the legalisation of some narcotics increasingly is being seen by regional leaders as a possible way to end the violence spawned by the cocaine trade.
Rich countries debating legalisation of marijuana also are watching the bill, which philanthropist George Soros has supported as an "experiment" that could provide an alternative to the failed United States-led policies of the long "war on drugs".
The bill gives authorities 120 days to set up a drug control board that will regulate cultivation standards, fix the price and monitor consumption.
The use of marijuana is legal in Uruguay, a country of 3.3 million people that is one of the most liberal in Latin America, but cultivation and sale of the drug are not.
Other countries have decriminalised possession and the Netherlands allows sale in coffee shops, but Uruguay will be the first to free the chain from growing to buying and selling.
Several countries such as Canada, the Netherlands and Israel have legal programmes for growing medical cannabis, but do not allow its cultivation for recreational use.
Last year, the US states of Colorado and Washington passed ballot initiatives to legalise and regulate the recreational use of marijuana.
Uruguay's leftist president, Jose Mujica, defended his initiative as a bid to regulate and tax a market that already existed, but was run by criminals.
"We have given this market as a gift to the drug traffickers and that is more destructive socially than the drug itself, because it rots the whole of society," Mujica told Argentine news agency Telam.
Mujica has yet to convince a majority of Uruguayans that legalisation is a good idea.
According to a recent opinion poll by Equipos Consultores, 58 per cent of Uruguayans oppose legalising the drug, although that was down from 68 per cent in a previous survey in June.