I know it is but I have a hard time believing this is the whole of her justification for instituting a new weapons ban (or actually that anyone buys it). From her summary
A Justice Department study of the assault weapons ban found that it was responsible for a 6.7% decrease in total gun murders, holding all other factors equal.
This looks like a very good “hard fact” but the very next line in the exact same study says
However, with only one year of post-ban data, we cannot rule out the possibility that this decrease reflects chance year-to-year variation rather than a true effect of the ban.
Get that? It says, there was a decrease in gun murders (note: not in overall murders) but its possible it just normal variation because its so small. She cites a study that is wishy-washy on its face because they are showing a trend with a single data point (1 year). You can’t show a trend with a single data point. Especially one small enough to be natural variation.
Don’t you think if there was a better study to cite, she would?
I’m not going to bother to quote the rest of her reasons that she claims “Assault weapon bans have been proven to be effective” I’ll summarize:
When we banned these guns, these guns were seen to be used less in the crimes we were concerned about. The police also noticed a drop in the rate that these guns were confiscated from criminals. We do not have any data that the crimes we were concerned with happened any less frequently or lessened their impact on civil society. The crimes still happened, they just didn’t happen with these specific guns anymore.
All of the data they show is that they took away the guns. Hey look! We banned them! Then we found people used them less! Huzzah!
They don’t have any data (because there isn't any) that shows that banning guns is effective for anything except banning guns.