There are a couple of principles that seem useful as we consider sensible measures to improve gun safety.
The first principle considers how much firepower should be in ordinary hands. Reasonable people would agree that there is a line where the capabilities of a firearm create more risks than benefits. For example, we sensibly limit the ownership of fully automatic firearms and other powerful weapons. Most people believe that the capabilities of assault-style semi-automatic weapons and weapons with massive ammunition clips go beyond the reasonable needs of ordinary households. A sensible approach to gun safety is to set a limit on capabilities; possession any firearm or component that exceeds those capabilities would require federal licensing, which in turn would require an extensive criminal and mental background check, special training, reporting mandates if the firearm or component is lost or stolen, and fees to cover the administration of these provisions.
The second principle considers who should be allowed to possess a gun in the first place. Most guns are kept and used for legitimate purposes. However, some guns are also used for illegitimate and offensive purposes. Criminals and people who lack the rational capacity to use a firearm responsibly should not have them. The problem is the people who shouldn't have access to guns aren't immediately distinguishable from people who should have access. Worse, methods of distinguishing different types of people (a) are imperfect (for example, no reasonable system will identify people with criminal intent but no prior criminal activity), (b) impose costs on the legitimate potential owners--the vast majority of the population, and (c) have to be nearly universal to be effective (the analogy is a fence that runs along three-quarters of a property line--with little effort someone can just walk around).
The U.S. currently requires some gun purchasers to undergo checks through the National Instant Criminal Background Check System (NICS). However, the system is far from universal. Federal regulations require licensed sellers to perform the checks, but depending on the state, other sales often go unchecked. The checks should be universal and national. This would raise the costs for some private transactions and reduce their convenience, but maybe not as much as some people think. For example, we have a system of notaries public that verify identities for legal documents. It's hardly a stretch to imagine a private system that could provide NICS verification. Gun shows could hire these verifiers to staff a booth and perform the checks for private sales and exchanges. Outside of gun shows, private seller and traders could go to a local verifier.
An additional problem with the NICS is that a subset of states have not cooperated in providing records. Financial incentives should be provided to obtain the necessary cooperation.
As if these impediments to keeping guns out of the hands of criminals weren't enough, the gun lobby has also worked to neuter the modest amounts of enforcement that are there by cutting its staffing and by denying it leadership. The country needs a functioning Bureau of Alcohol, Tobacco, Firearms and Explosives, and that Bureau needs a confirmed director. Conservative legislators have also worked to reduce funding for federal-local partnerships, like Project Safe Neighborhoods, that reduce gun trafficking and that promote the safer use of guns.
Taken together, how much would capacity restrictions, better checks, and more effective enforcement help to stem gun violence? Unfortunately, we shouldn't expect much impact--initially. America is awash in guns; all guns are capable of producing harm; and all guns can be misused. Restrictions on the most powerful guns would only put a small dent in overall gun ownership. More consistent and complete checks would slow the circulation of guns into the wrong hands but would not remove guns. Indeed, it is actually reasonable to suspect that things would initially get worse, as the announcement of any policy change would lead some people to speed up their transactions before the implementation date.
Over time, however, there could be improvements in safety, but realistically these improvements would be modest and gradual. The most noticeable direct improvement would come from choking off the supply of guns to criminals. In 2008, there were approximately 1,800 gun homicides committed in conjunction with another crime (74 percent of all homicides involving a felony) and approximately 900 gun homicides that were gang-related (92 percent of all gang-related homicides). These accounted for about one out of nine homicides committed in 2008. While tragic events, like the shooting in Newtown, CT, command our attend, an equivalent number of victims are gunned down in the commission of crimes or in gang murders every four days.
Limiting access to more powerful weapons might reduce the number of mass shootings, but as horrendous as these tragedies are, they account for only a small fraction of homicides each year. In 2008, 95.5 percent of all homicides involved a single victim; 3.7 percent involved two victims; and less than 1 percent involved three or more victims. The percentage of shootings involving extraordinary weapons is obviously even lower still. At its best, a completely effective ban on overly capable weapons would only save a few dozen lives. This doesn't mean that we shouldn't enact these steps--each life that we can save is precious. Realistically, however, the number that will be directly saved is modest.
A more promising improvement would likely be indirect. As fewer gangs and criminals possessed guns and perhaps as there were fewer headline-grabbing mass murders, the fear that motivates a large portion of gun ownership would subside. This indirect, albeit rational and voluntary, effect would lead to reductions in gun ownership and would greatly increase safety. Guns in the home increase the chances of accidental deaths and injuries, suicides, homicides, and violent intimidation without much demonstrable effect on crime deterrence, self-defense. Gun manufacturers would suffer, but the rest of us would benefit.
Restricting access to the most dangerous guns and keeping all guns out of the hands of the most dangerous people are sensible steps that would help stem gun violence, but they are far from a cure all. Hopefully, though, they would be a first step toward a substantially safer and saner country.
