If you need an economic argument for legalising marijuana in Australia, here it is: millions of tax dollars. The Parliamentary Budget Office (PBO) has released an estimate of how much the government could raise if a 10% goods and services tax (GST) was hypothetically placed on legalised household consumption of marijuana, and after federal law enforcement stopped going after marijuana related-crime. If all marijuana, cannabis and hemp consumption, cultivation and trade was legalised starting July 2017, the PBO said GST revenue would increase by around $650 million in the fiscal year 2015-16 budget forward estimates period, which runs through 2018-19. The expenses of the Australian Federal Police and Australian Border Force would also be reduced, among other agencies. See also: 11-year-old girl calls out Australian Prime Minister over same-sex marriage The estimate was worked out at the request of New South Wales' Sen. David Leyonhjelm, who has stated that marijuana should be legal, particularly for medical conditions and pain relief. "Of the $1.5 billion dollars spent annually on drug law enforcement, 70% is attributable to marijuana. That is an expense we do not need," he said in a parliamentary speech in July 2015. "If its consumption is legal, it can be taxed." Still, the PBO said the costing had "low reliability," given the uncertainly about the price and quantity of marijuana that would be consumed once it was legalised. The figures also assumed all states and territories would fully legalise the drug along with the commonwealth, among other conditions. It said the policy could increase marijuana consumption from around 333 tonnes in 2016-17 to 378 tonnes in 2017-18. While there has been little movement toward comprehensive marijuana legalisation in Australia, state and federal governments have been testing the waters for giving medicinal cannabis the go-ahead. In October 2015, Health Minister Sussan Ley announced the government would move to amend legislation to allow for the "controlled cultivation" of the plant in Australia for medicinal uses. (H/t: Fairfax Media) Have something to add to this story? Share it in the comments.