Both sides have repeatedly cited different studies and figures to support their claims, but unfortunately they are often taken out of context. It is often repeated that both gun ownership and gun violence in the United States are the highest in the developed world, with over 31,000 deaths in 2009. This is factually correct, but its implication is less clear. Despite the fact that the U.S. does lead the "developed" world in gun deaths, gun violence and gun ownership have been trending on two different paths. Although gun ownership has steadily increased in the last 30 years, gun violence has been decreasing along with violent crimes overall. The 31,000 death figure often cited also includes suicides, which is the majority (17,000). In those cases, there is no evidence that reducing the presence of firearms would make someone suddenly change their minds about committing suicide by another means. The implication that more guns equals more assault and murder does not have the support of empirical data.
If reducing the volume of guns reduced violence, then trends would be evident in other nations. You would intuitively expect to see lower violence levels in nations with very strict gun laws, but no such trends exist. There is no correlation that less guns equals less violence between nations with strong gun ownership and strong gun prohibitions. Belarus and Russia have a complete ban on owning a handgun. Belarus has a murder rate of 10.4 per 100,000, Russia has a murder rate of 20.5 per 100,000. Poland, with similar demographics, allows handgun possession and has a murder rate of only 1.9. Norway and Finland both have comparable gun ownership rates to the United States, (30% and 39% respectively, compared with 34% for the U.S.) yet have lower murder rates than the United States (2.0, 0.9 respectively, compared with 4.9 for the U.S.). If you operate under the assumption that the mere presence of guns would increase the crime rate, you would see evidence of such in European jurisdictions which vary widely from wide ownership of guns (France, Germany, Norway) to a complete prohibition on guns (Great Britain, Luxembourg) or even in jurisdictions within the United States, but no such correlation exists.
Does that mean, however, that any form of gun control would prove a fruitless inhibition of liberty? Not necessarily. There is a strong positive correlation between a history of violent behavior, criminal activity, and substance abuse with a strong disposition to commit a violent crime with a firearm. In studies of major metropolitan crime data, between 70-90% of murders involve people with prior arrests for drug offenses or other violent activity. Evidence shows that limiting access to firearms to people with a history of criminal activity and drug or alcohol abuse could provide meaningful results, unfortunately, many states' laws do not provide adequate prohibitions.
36 out of 50 states have no requirement for a background check whatsoever upon purchasing a firearm.While most states and the federal government have laws restricting possession of firearms by violent criminals, these laws are not effective when it is not a crime for someone to sell them a firearm. In most states, it would be legal to sell firearms to someone involved in criminal activity, or who has a mental impairment or a history of substance abuse, as there is no great burden placed on a seller of a firearm to ensure they are not selling weapons that could be used in criminal activity. A Johns Hopkins study found criminals easily obtain guns in a legal transaction by someone not required to do a background check. In this particular study of violent crimes using a firearm, 60% of the offenders were prohibited from owning a firearm, yet 96% of those individuals obtained the firearm from someone not required to do a background check. It was illegal for the criminal to buy the firearm, but not illegal for the seller to sell it to them. We're obviously not going to expect someone who is prohibited from firearm possession due to a criminal record to follow gun possession laws.
This does not prove that a universal background check system would eliminate most or even the majority of this type of crime, but it simply is not rational to make it easy for individuals with a history of psychopathic or violent behavior to obtain a weapon when you can place roadblocks to such possession without inhibiting law-abiding citizens from protecting themselves. Many criminals will still be able to obtain firearms through an illegal sale or trade or on the black market, but preventing otherwise law-abiding citizens from unknowingly selling a firearm to a criminal or knowingly selling a firearm to a criminal without fear of penalty should have some effect on reducing firearm possession by criminals. Expanding prohibiting criteria to encompass all violent crime and certain alcohol related offenses such as DWI violations would likely prevent firearms from going to people who have a much higher likelihood of committing gun violence. The old adage that gun laws only prevent law abiding citizens from protecting themselves is not true in all cases. The opposite is true here, strong criminal background checks and expanding activities that would prohibit one from owning a firearm would help prevent criminals from getting weapons and strengthen the gun owners' right to self protection.
The rhetorical devices on both sides tend to play on emotion and ignore the available data. The most concerning element of that is the possibility of enhancing gun policies that already work, such as universal background checks and tougher criteria for gun prohibition, is something everyone can agree on. However, there is no data that supports the notion that more guns means more crime, and there is a statistical correlation between increasing gun ownership and conceal carry among law abiding citizens and decreasing crime. The vast majority of gun owners will never commit a crime and should see their rights expanded, and at the same time we should not let a healthy defense of the Second Amendment get in the way of strong enforceable laws to prevent criminal possession of guns. However you view this debate, Americans are passionate for legitimate reasons and our best hope to start meaningful change is to remember this debate is about good citizens versus criminals, not about Democrats versus Republicans.