One of the guns that suspect James Holmes used in the Colorado theater massacre of at least 12 early Friday morning is quickly reigniting the gun-control debate.

The AR-15 is a semi-automatic assault rifle that is a civilian version of the military’s M-16. According to CNN, it’s capable of carrying up to 100 rounds. It shoots one bullet at a time that can “may go through two people” at once. And it’s legal in the United States.

After the Aurora Police Department revealed that this was one of the guns Holmes used, outrage ensued online, mostly because the gun would have been a lot harder to purchase under the Federal Assault Weapons Ban that expired in 2004. The American congress has not voted to replace the bill, which was enacted in 1994 but had a “sunset provision” that let it expire.

In 2004, presumptive Republican presidential nominee Mitt Romney signed a permanent assault weapons ban into law in Massachusetts. That included guns like the AR-15.

“I believe the people should have the right to bear arms, but I don’t believe that we have to have assault weapons as part of our personal arsenal,” he said on Fox News in 2004.

On Romney’s campaign website, he suggests that Congress does not need to revisit the assault weapons ban. His campaign website highlights legislation that “expanded the rights” of gun owners that Romney signed while he was governor, but does not mention the assault weapons ban.

When Obama was elected in 2008, he said he hoped a new assault weapons ban would be in place by the end of his first 100 days in office. He supports new legislation, but Congress has not brought a new bill to the floor. Agencies