“It’s a sweet little gun,” Martin Bryant said of his AR-15 semi-automatic assault rifle when being interrogated by police. Twenty years ago, on April 28, 1996, Martin took that gun and committed a massacre in the Australian state of Tasmania. Over 24 hours, in what became known as the Port Arthur Massacre, he killed 35 people and injured 23 more. The violence and senselessness of the act, the largest massacre in Australia’s post-colonial history, so shocked that nation that within 12 days, comprehensive gun-control legislation was agreed upon. There has not been another mass shooting in Australia since. Which brings us to Orlando, Florida, and another semi-automatic weapon.

About 10 days before he committed the single largest shooting massacre in modern U.S. history, Omar Mateen walked into the St. Lucie Shooting Center, in Port St. Lucie, Florida, and bought an AR-style semi-automatic rifle and a 9 mm semi-automatic pistol. “He passed the background check that every single person that purchases a firearm in the state of Florida undergoes,” store owner Ed Henson told the press. Mateen was a U.S. citizen, with a state-issued Florida photo ID permitting him to carry guns. He walked into Pulse, a gay nightclub in Orlando, on Latin Night, and opened fire. Forty-nine people were killed, and more than 50 were injured.

“In America, the background check consists of, usually, looking at a computer to see if someone has a criminal conviction. That’s not a background check,” Rebecca Peters of the International Action Network on Small Arms told us on the “Democracy Now!” news hour. “In New York City, if you want to apply to rent an apartment, if you want to apply to go to university, there’s a background check. The authorities talk to people who know you. They ask their opinion of you. And similarly, in Australia and most other developed countries, a background check consists of asking for references – your family doctor, talking to your spouse or your previous spouse, asking, ‘Is there any concern?’”

A more comprehensive background check on Omar Mateen might have exposed details, such as how he abused his first wife, Sitora Yusufiy, so severely that she left him after just four months of marriage. Or that Dan Gilroy, one of his co-workers at the security company Mateen worked at, G4S, felt that Mateen was “unhinged,” “unstable” and “full of rage,” a racist and a homophobe, as he told ABC News. Yet reports are that Mateen was seen at Pulse on numerous occasions, and used gay dating apps. Mateen, a New York-born U.S. citizen, the son of Afghan immigrants, was investigated twice by the FBI for potential terrorist sympathies or statements. Yet he bought two powerful semi-automatic weapons, with no problem.

In the wake of Australia’s Port Arthur massacre, Rebecca Peters led the national fight for gun control. “We had had a campaign for about 10 years at that time to reform the gun laws, which were weak in some states, and it was a patchwork across the country, as it is in the U.S.,” she told us. “In April of ‘96, this tragedy occurred ... at that moment, our prime minister said: ‘This is the time. After all this prevaricating, we’re going to do something.’” The Australian prime minister at the time was conservative John Howard.

Peters went on: “A crucial part of the new laws is proper checking of the background of people who are applying to have guns. It’s not only domestic violence, it’s also depression and alcohol abuse, and many other factors can make a person at risk of violence, not to mention people who have – who are vehemently racist or resentful.”

Guns are still legal in Australia, since, as Peters said, “the self-image of Australia is often sort of an outdoor guy on a horse with a gun type of thing, not too dissimilar from the traditional image of Americans.” In fact, iconic “Crocodile Dundee” Australian men supported the ban on semi-automatic weapons, arguing that “real men” didn’t need such weapons to survive in the Outback. Australia now has serious background checks, and semi-automatic weapons are illegal. When the law was passed, owners of guns like the AR-15 were legally compelled to sell them to the government, after which the weapons were destroyed.

As this column goes to press, U.S. Sen. Christopher Murphy, D-Conn., has launched a filibuster, vowing to speak, he said, “for as long as I can” to force a debate on gun control. Four years ago, he was in the U.S. House. Twenty schoolchildren and six adults were massacred at the Sandy Hook Elementary School in his district. The killer, Adam Lanza, used an AR-style semi-automatic weapon there, as James Holmes did in his shooting spree in the Aurora movie theater in Colorado earlier that year. These weapons would have been illegal under an assault-weapons ban that Congress let expire over a decade ago. We need a ban on semi-automatic guns, which are no more than weapons of mass destruction designed to efficiently kill as many people as possible.