What is an "assault weapon"? That was the question I addressed in a short article for the The Regulatory Review, at the University of Pennsylvania Law School. The Regulatory Review publishes short articles–about a thousand words–on a wide range of regulatory issues. In November, The Regulatory Review produced a nine-article series, Bringing Expertise to the Gun Debate.

My contribution was Defining "Assault Weapons". Surveying various "assault weapon" laws and bills, the article describes the always-shifting definitions. According to gun ban advocates, "assault weapons" have been claimed to include: air guns and paintball guns; most handguns; all semiautomatic rifles; most shotguns; all slide action shotguns; any semiautomatic the Secretary of Treasury wants to ban; guns listed by name; and guns with certain features, such as adjustable stocks.

The very heterogeneous group of so-called "assault weapons" has only two things in common. First of all, none of them are automatics or machine guns. Gun prohibition advocates have very effectively created and then exploited public confusion on this point. Second, none of the guns are "assault rifles," as that term has been defined by experts from the Defense Intelligence Agency. An actual assault rifle is capable of selective fire, meaning that it can fire automatically or semi-automatically with the flip of a selector switch; examples include the U.S. Army M-16, the Soviet AK-47, and the German Sturmgewehr.

In short, "Assault weapon" is just an epithet to stigmatize the largest possible number of guns and gun owners—the breadth of the definition of the moment depending on the politics of the moment.

The other articles from the Penn symposium are by Anthony Braga & Philip Cook (guns are more likely than other weapons to cause a fatality when used in a criminal attack); Robert Spitzer (the 1934 National Firearms Act is a good model for gun laws; the BATFE is underfunded and persecuted); James Jacobs (private sales of firearms should be outlawed); Joseph Blocher and Darrell A.H. Miller (scholars should contribute more to knowledge about gun policy); Jennifer Doleac (there are many effective means other than gun control to reduce gun deaths), David Abrams (data driven policy should impose heavy taxes on some guns and ammunition); Philip Cook & Jens Ludwig (gun misuse causes much economic harm); and Amanda LeSavage (the Consumer Product Safety Commission should be authorized require warning labels saying that guns make households less safe).