In 1996, the Australian government introduce a nationwide ban on what?

The Port Arthur massacre of 28–29 April 1996 was a mass shooting in which 35 people were killed and 23 wounded in Port Arthur, Tasmania. The murderer, Martin Bryant, pleaded guilty and was given 35 life sentences without the possibility of parole. Fundamental changes of gun control laws within Australia followed the incident. The case is the worst massacre in the modern history of Australia.

A redesign of the laws for all States and Territories of Australia had been prepared by officers and presented at a meeting of Police Ministers' in Launceston in 1995. It had been rejected by Tasmania.

Following the spree, the Prime Minister of Australia, John Howard, led the development of strict gun control laws within Australia and formulated the National Firearms Agreement, restricting the private ownership of semi-automatic rifles, semi-automatic shotguns and pump-action shotguns as well as introducing uniform firearms licensing. It was implemented with bipartisan support by the Commonwealth, states and territories. The massacre happened just six weeks after the Dunblane massacre, in Scotland, which claimed 18 lives, with U.K. Prime Minister John Major reaching out to his counterpart over the shared tragedies; the United Kingdom passed its own changes to gun laws in 1997.