So, when a gunman killed 35 people in 1996 with a semiautomatic rifle in the tourist town of Port Arthur, on the island of Tasmania, the Australian people decided it was time for a change. A new law, backed by a conservative prime minister, divided firearms into five categories. Some of the deadliest assault-style weapons and large ammunition clips are now all but impossible for individuals to lawfully own. Firearms are subject to a strict permitting process, and dealers are required to record sales, which are tracked by the national and territorial governments. What's more, the law encouraged people to sell their firearms back to the government, which purchased and destroyed about 700,000 of them.
The results are hard to argue with. According to a Harvard University study, 13 gun massacres (in which four or more people died) occurred in the 18 years before the law was enacted. In the 16 years since there has been none. Zero. The overall firearm homicide rate dropped from 0.43 per 100,000 in the seven years before the law to 0.25 in the seven years after. By 2009, the rate had dropped further, to just 0.1 per 100,000, or one per million.
In the USA, the 2009 firearm homicide rate was 3.3 per 100,000, some 33 times higher than Australia's.