In a discussion of how Vice President Joe Biden has taken a lead role in the push for gun control, Chris Hayes reminded viewers that the former senator spearheaded the 1994 Violent Crime Control and Law Enforcement Act, which included the now-expired assault weapons ban.

Gov. Dannel Malloy (D-CT) said that under the 1994 law, very large magazines were not legal, although it was "too broad" when it came to the definition of an assault weapon.

Speaking to the U.S. Conference of Mayors on Thursday, Biden said, "High capacity magazines don't have a practical sporting purpose or hunting purpose. As one hunter told me, if you've got twelve rounds, if you've got twelve rounds, it means you've already missed the deer eleven times. You should pack the sucker in at that point."

In 1994, Hayes said, many debated how to define assault weapons, "and I think, in retrospect, there was a lot about that that was quite porous, right?"

Mallow said that "people, interests, have worked on a definition that is wide enough to drive a truck through. And so, you know, it has to look like this and have one or two or three or four similarities with a military instrument. It's really what most states have gone to that have even tried to do it on their own. And it's just too wide, too broad."

"The definition was lobbied to death," he said later.

Hayes said of the AR-15, which was used in Newtown, "versions of that did exist in the assault weapon ban and other versions didn't. It was sort of modified to fit in under."

Neera Tanden, president of the progressive Center for American Progress, said that studies have shown that "when we had the assault weapons ban, the number of guns that were recovered from criminals that had assault weapon features were declining. It took a little while because it grandfathered a lot of ammunitions in, but it actually was effective."

Malloy said he recently spoke with an older Texas mayor who said that when he was growing up, his family had a gun that held five shots -- but two of those had to be sealed because of tougher gun laws.

Jen Psaki, former White House deputy communications director, said one of the major Republican arguments against an assault weapons ban is the difficulty in defining what an assault weapon is, an argument that she said some people can "fall prey to." People who "want this to happen need to, you know, watch out for that."

There has been much debate regarding whether the ban was effective. A 2004 study conducted by the Department of Justice was inconclusive: "Because the ban has not yet reduced the use of LCMs [large capacity magazines] in crime, we cannot clearly credit the ban with any of the nation’s recent drop in gun violence. However, the ban’s exemption of millions of pre-ban AWs and LCMs ensured that the effects of the law would occur only gradually. Those effects are still unfolding and may not be fully felt for several years into the future, particularly if foreign, pre-ban LCMs continue to be imported into the U.S. in large numbers," it read.

Sam Wang, a professor at Princeton University, analyzed deaths from mass shootings and found that deaths from such events almost tripled after the ban expired, while the number of shooting incidents almost doubled. However, the number of such gun deaths before the ban were did not differ substantially. Mass killings, he wrote, "are always with us, but advanced weaponry creates an efficiency of scale to allow the possibility of large killings."

Watch the video, via MSNBC, below.

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